Free online calculators for everyday decisions

Reputation Calculator

Check review-weighted ratings and the additional reviews needed for a target, using supplied counts, future-average scenarios and explicit limits.

Home & Construction

Pool Shock Calculator

Check ideal chlorine and product mass from verified pool readings, available-chlorine strength and liquid density, without choosing a shock target.

Food & Cooking

Sourdough Starter Calculator

Calculate sourdough feeding weights, reverse levain builds and final hydration including the retained seed, with clear ratios and worked examples.

Fixed Index Annuity Calculator

Compare annual index-credit scenarios using supplied returns, participation, spread, cap and fees, with auditable yearly account-value results.

Love Calculator on Paper

Follow FLAMES and LOVES paper games with name-letter counts and reproducible steps. Entertainment only, with no compatibility or relationship claims.

Sports

Bowling Handicap

Calculate bowling handicap per game and series with your league basis, percentage, whole-pin average, optional cap and scratch scores.

Crafts

Quilt Binding

Plan straight-grain quilt binding strips and fabric yardage with usable fabric width, explicit join losses, tail allowance and metric inputs.

Random Birthdays

Generate fictional birthdays within an inclusive date range, show age on a chosen reference date, prevent duplicate dates and download CSV.

Legal Day Counts

Check FRCP-style calendar-day endpoints with weekends, standard federal observed holidays, supplied court exclusions and explicit verification.

Construction

Brick Wall Takeoff

Estimate brick wall quantities using actual brick face dimensions, mortar joint width, opening deductions, independent leaves and waste allowance.

Bra Size Chart

Estimate a US and UK bra chart starting size from inches or centimetres, with explicit rounding, cup differences and sister-size options.

Science

Q10 Aging Scenario

Compare chamber days and reference-duration equivalents with a supplied Q10 factor, verified temperature assumptions and explicit protocol limits.

Construction

Pavers and Base

Estimate rectangular paver counts, supplied base and bedding ordering volumes, and container counts with explicit joints and allowance.

Home Rent vs Buy

Compare home renting and buying with mortgage balance, closing and selling costs, rent changes, ownership expenses and opportunity-cost scenarios.

Compound Interest

Model compound growth with monthly contributions and an explicit nominal or effective annual return, including independent user-assumed ETF scenarios.

Savings Goal

Find the monthly amount required to reach a savings target by a chosen deadline.

Mortgage Payment

Estimate principal and interest, then add user-entered annual property tax and homeowners insurance to compare a broader monthly mortgage cost.

Discount

Calculate the sale price, amount saved and final price after an optional tax or service rate.

Sales Tax & VAT

Use this online sales-tax/VAT calculator to add a user-verified rate to net price or remove included tax from a gross amount, without assuming local law.

Profit Margin

Calculate selling price from cost and markup, or derive markup and gross margin from a known selling price, with currency-neutral outputs.

Break-Even

Calculate whole-unit break-even sales, theoretical volume, revenue and profit at planned sales from fixed costs, unit price and variable cost.

Tip

Calculate a tip, total bill and per-person payment for restaurants and services worldwide.

Split Bill

Divide a shared bill after adding a tip or service percentage and optional shared extras.

Unit Price

Compare two pack sizes by cost per unit to identify the lower-priced quantity.

Work Hours

Calculate paid shift hours from 24-hour times or add hours to the local clock; optionally estimate gross earnings from an hourly rate.

Download Time

Estimate how long a file takes to download from its size, connection speed and practical efficiency.

Running Pace & Splits

Calculate running pace or generate cumulative even-pace race splits from distance, target time and a chosen kilometre or mile split interval.

Aspect Ratio

Calculate a missing image or video dimension from its aspect ratio, or resize the frame while preserving its original proportions.

Fuel Economy

Convert between litres per 100 km, kilometres per litre and miles per US gallon.

Personal Cash Runway

Estimate how many months your available savings can cover an ongoing monthly cash shortfall.

Business Cash Runway

Estimate how long a business can operate from available cash at its current net monthly burn.

Burn Rate

Calculate gross burn, net burn and the percentage of opening cash consumed each month.

Emergency Fund

Set a configurable emergency-fund target and measure current savings coverage in months.

Sinking Fund

Calculate the regular contribution needed for a known future expense, with optional interest.

Debt-to-Income Ratio

Compare required monthly debt payments with gross monthly income using front-end and total DTI views.

Loan Comparison

Compare monthly payments and total interest for two fixed-rate loans over the same term.

Effective Interest Rate

Convert a nominal annual rate and compounding frequency into an effective annual rate.

Loan Early Payment

Estimate payoff time and interest savings from adding a fixed extra amount to each loan payment.

Invoice Financing Cost

Estimate the cash advanced, financing fee and implied annualized cost of financing an invoice.

Late Payment Interest

Calculate simple late-payment interest and an optional fixed recovery charge from user-entered terms.

Subscription Cost

Project the multi-year cost of recurring subscriptions with an optional annual price increase.

Salary to Freelance Rate

Translate an annual employee salary target into a sustainable freelance hourly rate.

Retirement Savings Runway

Estimate how long retirement savings last with monthly withdrawals, a constant assumed return, optional withdrawal inflation and a bounded projection horizon.

Recurring Expense Impact

Project the long-term cash cost of a recurring monthly expense and optional annual price growth.

Lifestyle Inflation

Measure how much monthly spending increased after an income change and project its annual effect.

Rent Affordability

Estimate a cautious rent ceiling from monthly income, essential commitments and a chosen income percentage.

Goal Timeline

Estimate how many months regular contributions may take to reach a financial target.

Budget Percentage

Convert monthly spending and saving amounts into percentages of take-home income.

Net Worth Change

Compare assets and liabilities at two dates to measure the amount and percentage change in net worth.

ROAS

Calculate return on ad spend, revenue per advertising dollar and the revenue change needed to reach a target ROAS.

Break-Even ROAS

Calculate the minimum ROAS required to cover product cost, shipping, payment fees and expected returns before advertising profit begins.

Cost per Acquisition

Calculate advertising cost per conversion or acquisition and compare the result with a target CPA for any campaign.

Customer Acquisition Cost

Calculate blended customer acquisition cost from marketing and sales spending, then compare it with customer value or a target CAC.

Customer Lifetime Value

Estimate revenue and gross-profit customer lifetime value from average order value, purchase frequency, lifespan and margin.

Average Order Value

Calculate average order value from revenue and completed orders, then estimate the revenue effect of a higher AOV target.

Profit per Order

Calculate net contribution per order after product cost, shipping, payment fees and advertising cost in any currency.

Discount Profit Impact

Calculate how a percentage discount changes unit profit and how many additional sales are required to preserve gross profit.

Return & Refund Impact

Estimate revenue lost to returned orders, retained revenue and unrecoverable return costs from an e-commerce period.

Inventory Reorder Point

Calculate a reorder point from average daily demand, supplier lead time and safety stock for global inventory planning.

Dimensional Weight

Calculate dimensional shipping weight from package dimensions and a carrier divisor, then compare it with actual scale weight.

Ad Budget & Sales Target

Estimate orders, advertising budget and website traffic needed to reach a sales target from AOV, conversion rate and target CPA.

Snowball vs Avalanche

Compare debt snowball and debt avalanche payoff strategies using balances, rates and an extra monthly payment.

Minimum Payment

Estimate payoff time and interest when a credit-card balance is repaid using a percentage-based minimum payment.

Card Payoff

Calculate how long it may take to pay off a credit card and estimate interest using a fixed monthly payment.

Card Utilization

Calculate utilization for one credit card and across total revolving credit limits before a statement is reported.

Investment Fees

Compare long-term investment growth before and after annual fund or adviser fees using regular contributions.

Real Return

Convert a nominal investment return into a real return after inflation and optional annual fees.

DCA Calculator

Project the future value of equal recurring investments using a configurable return and contribution period.

Lump Sum vs DCA

Compare investing available cash immediately with investing the same amount gradually over a selected schedule.

Coast FIRE

Estimate whether current investments could grow to a retirement target without additional contributions.

FIRE Number

Estimate a financial-independence portfolio target from annual spending and a chosen withdrawal rate.

Savings Rate

Calculate the percentage of take-home income saved or invested and project the annual amount.

Dividend Reinvestment

Project portfolio value and dividend income when distributions are reinvested over time.

Portfolio Rebalancing

Calculate trades required to restore two portfolio assets to selected target percentages.

Capital Gains

Calculate gross capital gain, taxable gain and an estimated tax amount using user-entered adjustments and rate.

Tiered Commission

Calculate sales commission across progressive tiers and show the blended commission rate.

Pro Rata

Calculate a fair pro rata amount for part of a period from the full-period value and eligible days, including prorated salary and billing examples.

Pay Raise

Compare old and new pay to calculate a salary raise amount, wage increase percentage and the change on a consistent pay-period basis.

Overtime Pay

Estimate regular pay, overtime pay and total gross earnings using an editable overtime multiplier.

Invoice Due Date

Find an invoice payment deadline from an invoice date and user-entered payment term.

Net Terms Date

Compare Net 30, Net 60 and Net 90 deadlines from the same invoice or delivery date.

Invoice Discount

Calculate an early-payment discount, customer payment and supplier cash received from invoice terms.

Project Profit

Calculate freelance project profit after labour value, platform fees and direct expenses.

SaaS Pricing

Estimate a subscription price from per-customer cost, target gross margin and fixed monthly costs.

Debt Service Coverage

Calculate debt service coverage ratio from operating income and required principal and interest payments.

Processing Fees

Calculate percentage and fixed payment-processing fees, net proceeds and effective fee rate.

College Admission Chances

Estimate a broad college acceptance range from GPA, test percentile, course rigor, activities and the target college acceptance rate.

Lawyer Cost

Estimate real estate lawyer fees from a flat fee, hourly work, closing support and additional legal costs.

Lease vs Buy

Compare 36-month lease and purchase cash costs including remaining loan principal, resale value and explicit additional costs in one currency.

Seller Net Sheet

Estimate a property seller's net proceeds after mortgage payoff, commission, closing costs, credits and other deductions.

Seller Financing

Calculate a seller-financed property's payment, balloon balance, total interest and cash received from buyer terms.

Rate Buydown

Compare mortgage payments and estimated savings from discount points or a temporary interest-rate buydown.

First-Lien HELOC

Estimate interest-only and repayment payments for a first-lien home equity line using user-entered balances and rates.

Date From Today

Find future or past dates from day, week or month offsets and calculate elapsed days between dates.

Payment

Estimate a fixed periodic loan payment or annuity payout from principal or present value, annual interest rate, repayment term and payment frequency.

Interest

Calculate interest earned and ending balances with simple or compound growth, CD or FD nominal rates, quoted APY, or an implied rate from two balances.

Ratio

Simplify, scale, compare and convert ratios between equivalent ratios, fractions and percentages with a clear mode for each task.

Age

Calculate chronological age from a birth date to a chosen date in completed years, months and days.

Period

Estimate the next menstrual period and cycle dates from the first day of the last period and usual cycle length.

Random Number

Generate random integers inside a chosen inclusive range, including common 1–100 and four-digit use cases.

Cubic Yard

Calculate rectangular material volume in cubic yards from feet, with cubic-foot and metre equivalents and a user-entered purchasing allowance.

Gravel & River Rock

Estimate gravel, crushed stone, pea gravel or river rock volume and approximate weight from area, depth and material density.

Army Body Composition

Calculate the U.S. Army 2026 waist-to-height ratio screening value using waist at the navel and standing height.

401(k)

Project 401(k) growth, compare a Roth and traditional contribution under entered tax assumptions, or estimate taxes and penalties on a planned withdrawal.

Sand

Estimate sand volume and approximate weight from area, depth and bulk density for paving, landscaping or construction planning.

Right Triangle

Solve a right triangle from two legs, a hypotenuse and leg, or a leg and acute angle; show sides, angles, area and perimeter.

AP World Score

Estimate an AP World History: Modern composite percentage from section performance using the current College Board exam weights.

GPA

Calculate weighted average GPA from course grade points and credit weights.

Square Footage

Calculate rectangular square footage and optionally total multiple identical areas.

One Rep Max

Estimate a one-repetition maximum for bench press, squat or deadlift from a completed set, using the Epley equation.

Triangle

Calculate triangle area and perimeter from three side lengths using Heron's formula.

Molecular Weight

Calculate molecular weight and molar mass from a chemical formula with grouped atoms, hydrates, element breakdown and mass percentages.

Bowling Score

Calculate a simple bowling total from entered frame scores for quick score checking.

Air Force PT Test

Add entered Air Force fitness component points into an estimated total without assuming current pass standards.

Square Root

Calculate a principal square root and square of a non-negative number, including searches for calculateur racine carrée.

Fraction

Add, subtract, multiply or divide two fractions using numerator and denominator inputs.

How Many Years

Calculate elapsed years between two calendar dates.

Cylinder Volume

Calculate cylinder volume and surface area from radius and height.

Asphalt

Estimate asphalt pavement volume, compacted mass, explicit material allowance and supplied material cost from area, thickness and supplier density.

AP Biology Score

Estimate an AP Biology practice composite percentage from section performance without claiming an official 1–5 conversion.

Women's BMI

Calculate adult BMI from measured weight and height, or find the weight corresponding to a supplied BMI, with clear screening and target-weight limits.

AP Chemistry Score

Estimate an AP Chemistry practice composite percentage from section performance without claiming an official 1–5 conversion.

Concrete

Estimate slab, Sonotube, and concrete block volume, add a project price, or total block weight from a supplied per-block weight.

NPV

Calculate net present value from an initial investment, recurring cash flow, discount rate and number of periods.

Weeks

Convert a number of days into weeks and remaining days.

Half Birthday

Find the date approximately six calendar months after a birth date.

Paycheck Hours

Estimate gross paycheck from hours worked, hourly rate and optional overtime hours.

Dog Pregnancy

Estimate a dog whelping window from breeding or veterinarian-established ovulation dates, keeping their different timing assumptions explicit.

Binary

Convert a binary value to decimal and show its hexadecimal representation.

Paycheck Estimator

Estimate gross and net paycheck from pay rate, hours and an entered deduction percentage.

Pool Salt

Estimate salt to add to a pool from water volume, current salt level and target salt level.

Rafter Length

Estimate common-rafter length from horizontal run and roof rise.

Stair

Estimate stair riser count, riser height and total run from total rise and preferred dimensions.

Scientific Notation

Convert a number to scientific notation and show its coefficient and base-10 exponent.

Grade

Calculate a current weighted grade or the score needed on a final exam to reach a target course grade.

Decimal Time

Convert decimal hours to hours, minutes and seconds, or convert an hours-and-minutes duration to decimal hours.

MAGI

Estimate modified adjusted gross income from AGI plus user-entered applicable add-backs for planning scenarios.

Money Market

Project a money-market balance from starting deposit, recurring contributions, APY and time.

Confidence Interval

Estimate a normal-approximation confidence interval for a sample mean from mean, standard deviation, sample size and confidence level.

Superscript

Convert supported letters and numbers into copyable Unicode superscript characters.

ERA

Calculate baseball earned run average from earned runs and innings pitched.

AP Statistics Score

Estimate an AP Statistics practice composite from section performance without claiming an official 1–5 cutoff.

GCF

Find the greatest common factor of two integers using the Euclidean algorithm.

APR

Estimate annual percentage rate from loan amount, finance charges and term using an iterative payment-equivalent calculation.

Wire Size

Estimate conductor voltage-drop requirements and compare common copper wire gauges for planning.

Cone Volume

Calculate cone volume from radius and height and show the underlying formula.

Normal CDF

Estimate cumulative probability for a normal distribution from x, mean and standard deviation.

Matrix Inverse

Calculate the inverse of a 2×2 matrix and determinant when an inverse exists.

Voltage Drop

Estimate circuit voltage drop and percentage drop from current, one-way length and conductor resistance.

Fill Dirt

Estimate fill-dirt volume in cubic feet and cubic yards from area dimensions and average fill depth.

Board Foot

Calculate lumber board feet from thickness, width, length and quantity.

Circle Skirt

Calculate the waist radius and cutting radius for quarter-, half-, three-quarter- or full-circle skirt patterns, with fabric-width guidance.

Cross Stitch

Convert a cross-stitch design's stitch width and height into finished fabric dimensions using the fabric count and an edge margin.

Hypergeometric

Calculate exact or cumulative probabilities for drawing a chosen number of successes from a finite population without replacement.

Wall Studs

Estimate the number of wall studs from the total wall run, on-center spacing, extra studs for openings and a material allowance.

Soffit

Estimate soffit area, panel rows and linear footage from total eave length, soffit projection, panel coverage and a waste allowance.

AP English Language Score

Estimate an AP English Language and Composition practice composite from multiple-choice questions correct and three free-response rubric scores.

Money Counter

Count bills and coins by entering matching denomination and quantity lists. Totals stay currency-neutral so you can use any currency.

Soil

Estimate loam or soil volume for a rectangular bed in yards and metres, with explicit allowance and optional weight from a supplied bulk density.

FFMI

Calculate fat-free mass index from body weight, height and entered body-fat percentage.

Hex

Convert hexadecimal values to decimal and binary, or perform basic arithmetic with hexadecimal integers.

Dunk

Compare standing reach plus vertical jump with a basketball rim to estimate the clearance available for a dunk.

Mare Gestation

Estimate a mare's foaling date and a broad planning window from the breeding date.

Linear Feet

Calculate total linear feet from repeated pieces measured in feet and inches.

Water Intake

Compare an adult's entered daily water intake with National Academies reference adequate intakes for total water from food and beverages.

Steps to Miles

Convert steps to miles or miles to steps using your own average step length.

Minecraft Circle

Generate a pixel-style Minecraft circle or filled disk as a block grid for building plans.

Density Altitude

Estimate density altitude from pressure altitude and outside-air temperature using the common rule-of-thumb approximation.

Height

Estimate an adult height target from biological parents' heights using the traditional mid-parental-height method.

Weighted Mean

Calculate a weighted mean from paired values and weights, such as grades weighted by credits or measurements weighted by sample size.

Yardage

Estimate fabric yardage for repeated rectangular pieces across a usable fabric width, comparing both cutting orientations.

Mean and Standard Deviation

Calculate mean, sample or population standard deviation and standard error of the sample mean from observed data using stable, validated arithmetic.

Visceral Fat

Estimate visceral adipose tissue area from waist, proximal thigh, age, BMI and sex using a published anthropometric equation.

Body Fat — U.S. Navy Estimate

Estimate body-fat percentage with the classic U.S. Navy circumference equations using height, waist or abdomen, neck and (for women) hip measurements.

Sourdough

Scale sourdough dough weight, hydration, prefermented flour and salt while accounting for the flour and water already in your starter.

Audiobook Speed

Find audiobook listening time and time saved at your chosen playback speed, including content you have already completed.

Area and Surface Area

Calculate plane area or total surface area for common shapes, with separate dimension labels for rectangles, circles, cubes and other solids.

Body Surface Area

Estimate body surface area in square metres using the Mosteller formula from height in centimetres and body weight in kilograms.

Roof Area

Estimate roof area, roofing squares, supplied shingle-package coverage and replacement cost, or calculate pitch from measured rise and horizontal run.

Corrected Calcium

Calculate the legacy albumin-adjusted calcium estimate in paired US or SI units, with clear limitations against measured ionized calcium.

Grade Curve

Apply an explicit grade curve to a list of scores by adding points, shifting the highest score or moving the class mean to a target.

PT-141 Dosage

Check entered dose spacing and monthly counts against Vyleesi label limits, without recommending a PT-141 dose or reconstitution regimen.

BTU

Estimate room air-conditioner BTU capacity from an official area table, or calculate heating output from your own design load per square foot.

Arrow Speed

Calculate average arrow speed from measured flight distance and elapsed time, then estimate kinetic energy using entered arrow mass.

Volume

Calculate solid or water-container volume for boxes, cubes, cylinders, cones, spheres, ponds and hollow tubes, with litres and gallon conversions.

Productivity

Calculate completed output per labor-hour, total labor input and performance against your entered productivity target using consistent units.

Time Between

Calculate elapsed days, hours, minutes and seconds between two UTC date-times, including intervals across midnight or calendar boundaries.

Blood Pressure by Age

Classify an adult blood-pressure reading using AHA categories while explaining why adult thresholds are not raised simply because age increases.

Baby Percentile

Estimate WHO baby weight-for-age percentile at exact monthly ages from birth to 24 months using sex-specific published LMS reference values.

Calories Burned

Estimate walking, cycling, running or treadmill calories from adult MET references, body weight and duration, with a measured-cadence walking step mode.

Pine Straw

Estimate whole pine straw bales from bed dimensions, your supplier’s coverage at the intended depth and an explicit waste allowance.

Ohms, Watts & Amps

Solve resistive DC values or convert watts and amps using voltage, with explicit RMS power-factor modes for single-phase and balanced three-phase AC.

Fence Post Depth

Compare a selected embedment guideline with your entered local minimum depth, then estimate excavation depth including a gravel layer.

Lead Time

Add sequential order-processing, production, transit and receiving durations to calculate a transparent calendar-day lead-time estimate.

Recessed Light

Estimate a recessed-light count from room area, fixture lumens, target lux and a supplied utilization and maintenance factor.

Partial Fraction

Decompose a rational polynomial over supplied real linear factors, including repeated roots and an improper polynomial quotient.

Implicit Differentiation

Differentiate a supported polynomial equation in x and y, show both partial derivatives and check the slope at a supplied point.

Greek Gematria

Add traditional Greek letter values with accent and case normalization, showing the total and a transparent letter-by-letter breakdown.

Time Off

Project a PTO balance from current hours, accrual per pay period, future periods, planned leave and an optional balance cap.

Decimals

Add, subtract, multiply or divide plain decimals using integer-based arithmetic, with an exact fraction and explicit output rounding.

VPD Calculator

Calculate air or leaf vapor pressure deficit in kPa, or relative humidity from air temperature and dew point, with explicit FAO formula assumptions.

Lifestyle

Goat Gestation Calculator

Estimate a goat kidding date and a 145–155-day planning window from a recorded breeding date, with clear limits on conception and pregnancy certainty.

50 to 1 Gas Oil Mix Calculator

Calculate two-stroke oil volume for a verified gasoline-to-oil ratio, including 50:1, using litres, US gallons or imperial gallons with clear units.

Macro Calculator

Calculate protein, fat and carbohydrate grams from your supplied calorie baseline and energy shares, with explicit user-chosen surplus or deficit scenarios.

Macroeconomics Calculator

Calculate expenditure GDP from consumption, investment, government spending, exports and imports using consistent supplied national-account amounts.

Vinegar Carbon Dosing Calculator

Scale a supplied aquarium vinegar protocol by measured water volume and compatible labeled acidity; no universal mL-per-ppm nitrate dose is inferred.

Simplifying Radical Expressions Solver

Simplify sums of integer square-root terms exactly by extracting square factors and combining like radicals, with a bounded parser and clear syntax.

Redacted Text Generator

Generate a separate redacted plain-text copy by replacing supplied literal phrases locally, with match counts, reviewable output and a TXT download.

Lifestyle

Wedding Liquor Calculator

Estimate whole spirit bottles from a supplied adult guest plan, liquor share, measured pour volume and bottle size, with transparent purchasing arithmetic.

ABG Calculator

Calculate uncorrected anion gap without potassium and the educational ABG pH relationship using explicit units, sample-basis checks and clinical limits.

Percent Calculator

Calculate percent difference, percentage change, parts, reverse percentages and time shares with clear formulas and a choice of calculation modes.

Mulch Calculator

Estimate mulch in cubic yards, cubic feet and whole bags from bed dimensions, finished depth, bag volume and an explicit allowance you control.

Concrete Block Calculator

Calculate cement or concrete wall block counts from net wall area, nominal modular face dimensions, opening area and an explicit ordering allowance.

Basis Points Calculator

Convert basis points to percent or decimals, compare rate changes, apply a BPS adjustment and estimate simple amount impact with explicit inputs.

Rounding Calculator

Round exact decimal numbers to places, tens, hundreds or significant figures with explicit half-away-from-zero and half-to-even tie rules.

Tire Size Calculator

Compare metric tire diameters, sidewall heights, circumference and ideal speed ratios, with millimeter-to-inch conversion and clear fitment limits.

Anniversary Calculator

Find completed annual anniversaries, the next anniversary date and days remaining using Gregorian dates and an explicit February 29 convention.

Science

GC Content

Calculate DNA or RNA GC content, base counts and GC skew with explicit handling of unresolved N bases and one optional FASTA record.

LLC Tax Reserve

Model an LLC tax cash reserve using your supplied profit share, effective reserve rate, known charges and payments, with clear classification limits.

Wainscoting Layout

Calculate equal clear wainscoting panel widths from your wall length, end margins, stile width and panel count, with a reproducible layout check.

Science

Charles’ Law

Solve Charles’ law for initial or final volume or Kelvin temperature at constant pressure, using three known values and explicit ideal-gas limits.

Crypto Conversion

Convert a supplied token quantity or quote-currency budget using your manual unit price and proportional fee, with no live OVO price assumption.

Minecraft Sphere

Generate solid or hollow Minecraft-style sphere layers, count blocks and export zero-based coordinates using a disclosed voxel rule and diameter.

Basic Calculator

Use a simple calculator for addition, subtraction, multiplication, division, parentheses and literal percentages, with clear precedence and input limits.

New Jersey Tax

Estimate 2025 New Jersey resident income tax using the official tax table or rate schedule, filing status and your supplied credits and payments.

Sports

Men’s Decathlon Scoring

Calculate men’s decathlon event points from recorded performances using the combined-events coefficients, event units and integer truncation.

Music

Dotted Note Duration

Convert a dotted note into quarter-note beats, seconds and milliseconds from an explicit tempo, note denominator and augmentation-dot count.

Matrix Basis, Rank and Null Space

Find numerical RREF, rank, pivot columns and bases for column, row and null spaces of a real matrix, with a disclosed pivot tolerance.

Complex Number Arithmetic

Add, subtract, multiply or divide two complex numbers and inspect the real part, imaginary coefficient, modulus and principal argument.

Measured Snow Weight and Surface Load

Calculate measured snow mass, weight and surface pressure from depth and density or water equivalent, with area and explicit gravity units.

Animals

Labrador to Human Age Comparison

Apply the published Labrador epigenetic age comparison using natural logarithms, with breed confirmation and clear population limits.

Sports

Golf Handicap and Score Differential Worksheet

Calculate an 18-hole score differential or inspect raw index arithmetic from recorded differentials, with current count rules and scope limits.

Absolute Neutrophil Count

Calculate ANC from a reported white-cell count and neutrophil percentages, with explicit laboratory units and a check against double-counting bands.

Revised Harris–Benedict Resting Energy

Estimate adult resting energy with the 1984 revised Harris–Benedict coefficients, explicit units and no hidden activity or intake multiplier.

Adult Shoe Size Converter

Compare adult US, UK, EU and CM/JP labels in a sourced Nike chart, with measured foot-length lookup and explicit brand-specific limits.

Food Energy and kcal–Calorie Conversion

Convert kcal, small calories and kJ, or calculate supplied food-composition energy with EU Annex XIV factors and explicit portion scaling.

Taxable Income Arithmetic Worksheet

Reconcile supplied includible income, assessed adjustments and allowed deductions into a taxable subtotal without inventing eligibility or rates.

Texas Retail and Dealer Vehicle Sales Tax

Calculate Texas taxable retail or dealer-vehicle sales tax with explicit local-rate input, taxable charges and scoped trade-in treatment.

2025 NYC Resident Income Tax

Calculate 2025 New York City full-year resident tax before credits from the official city table or schedule, with filing-status and residency gates.

Clothing Size

Match measured bust or chest, waist and hip to your own brand’s size-range chart, with per-row comparisons and no invented body-shape labels.

Lean Body Mass

Estimate adult lean body mass with the published Boer equation, showing the coefficient set, lean share and limits of an equation estimate.

Point-Mass Center of Mass

Find the three-dimensional center of mass of supplied positive point masses, with total mass, first moments and a reproducible coordinate convention.

Construction Crew Size Planning

Estimate whole workers needed for supplied productive labour hours and a work window, with availability, rounded capacity and paid-hour cost.

Excavation Swell and Haul Trip

Estimate loose excavation volume, conserved material mass and truck trips from supplied swell, density, volume capacity and payload limits.

Vector Dot Product, Cross Product and Projection

Calculate 3D dot and cross products, vector magnitudes, the angle between nonzero vectors and the projection of one vector onto another.

Five Number Summary

Find minimum, quartiles, median, maximum and IQR from a numeric list, with two explicit quartile conventions and outlier fences.

Average Time

Average MM:SS or HH:MM:SS durations, optionally weight observations, and compare the mean with the unweighted elapsed total.

Integer Exponent

Evaluate integer powers and combine same-base products, quotients or nested powers, with reciprocal notation for negative exponents.

Stem and Leaf Plot

Generate a sorted stem-and-leaf display from nonnegative observations, with an explicit decimal leaf unit and a reproducible key.

Energy

Battery Runtime

Estimate constant-load battery runtime from Ah or Wh, usable capacity, conversion efficiency and watts, with explicit energy assumptions.

Dilution Ratio

Calculate concentrate and diluent volumes from a final mixture and an explicit parts convention, without assuming product strength or dosing.

Fixed Coupon Bond Price

Price a fixed-coupon bond at a coupon date from face value, coupon, nominal yield, remaining periods and payment frequency.

Cartesian Distance — 2D and 3D

Calculate straight-line distance between Cartesian points in two or three dimensions, with coordinate differences and squared distance.

BPM — Timed Beat Intervals

Convert a timed count of beat intervals to beats per minute, with an explicit endpoint convention and a millisecond interval output.

Food Protein — Label-Based Portions

Total food protein from label grams and consumed portions, with per-row contributions and an optional user-supplied target comparison.

Force, Mass and Acceleration

Solve Newton’s second law for net force, mass or signed acceleration in SI units, with explicit direction and zero-acceleration checks.

Kinetic Energy

Calculate translational kinetic energy, mass or speed using the classical one-half mv² relation, with SI units and inverse checks.

Momentum and Impulse

Find signed linear momentum, impulse and average net force from a constant mass, initial and final velocities and a positive time interval.

Work and Average Power

Calculate work by a constant force at an explicit angle to displacement and its average power over a supplied positive time interval.

Gravitational Potential Energy

Find the signed change in gravitational potential energy and opposite work by gravity from mass, height change and supplied local gravity.

Hooke’s Law and Spring Energy

Solve signed restoring force, stiffness or displacement for an ideal linear spring and calculate its elastic potential energy in SI units.

Ideal Gas Law

Solve absolute pressure, volume, moles or absolute temperature with PV = nRT using explicit SI units and positive-domain validation.

Resting Energy: Mifflin–St Jeor

Estimate adult resting energy with the published Mifflin–St Jeor equation, showing inputs, population limits and no activity multiplier.

Rockport VO₂ Max

Estimate VO₂ max from an already completed one-mile Rockport walk record, with original adult population scope and explicit equation units.

2026 RMD: Uniform Lifetime Table

Calculate 2026 owner-account RMD arithmetic using the IRS Uniform Lifetime Table, with required eligibility confirmation and a prior-year balance.

Trigonometric Functions

Calculate sine, cosine, tangent and principal inverse angles with an explicit degree or radian setting and domain checks.

Slope

Find rise over run, line angle and Cartesian distance between two points, with explicit vertical-line and identical-point handling.

Rental Property Cash Flow

Model rental cash flow, net operating income, cap rate and cash-on-cash return from supplied rent, vacancy, costs and capital.

Resistor Color Code

Decode four- or five-band resistor colors into nominal ohms and tolerance limits using an explicit digit and multiplier convention.

Quadratic Equation

Solve numeric quadratic equations with real or complex roots, including repeated roots, linear reductions and degenerate equations.

Density, Mass and Volume

Solve physical density, mass or volume in SI units from two compatible supplied measurements, with positive-density and zero-volume checks.

Net Carbohydrate

Apply an explicitly supplied fiber and sugar-alcohol subtraction convention to one food label, with serving scaling and consistency checks.

Least Common Multiple

Find the exact least common multiple and greatest common divisor of up to 100 nonnegative whole numbers, including large integer text.

Dice Sum Probability

Compute exact outcome counts and sum probabilities for fair independent numbered dice, with exactly, at-most and at-least comparisons.

Nth Root

Find a real cube or higher-degree root with an integer degree, signed odd-root handling and a power reconstruction check.

Title Case Converter

Convert English text using simple headline or every-word capitalization while preserving punctuation and whitespace for manual review.

Sequence Sum

Calculate the finite sum and final term of an arithmetic or geometric sequence from a first term, step or ratio and term count.

Lease Buyout

Compare a supplied lease buyout quote with vehicle value and model financing, including separately supplied fees, tax and down payment.

Half-Life

Model constant exponential decay or infer a mathematical half-life from initial and remaining quantities over a supplied elapsed interval.

Acreage

Calculate acreage and area units from an ordered measured plot boundary in feet or metres, with crossing-boundary validation.

Annualized Return

Convert supplied starting and ending investment values over a stated year interval into an endpoint annualized return, without cash-flow assumptions.

Time Value of Money

Solve present balance, future balance or regular contribution using a supplied per-period rate, fixed period count and payment timing.

Prime Factorization

Factor a positive whole number up to ten billion into exact prime powers and report its positive divisor count and prime classification.

IPv6 Subnet

Find an IPv6 prefix block, exact address count and equal child-block count using 128-bit integer arithmetic and normalized hexadecimal text.

Bandwidth Requirement

Estimate aggregate traffic and modeled link capacity from concurrent streams, supplied rates and a maximum utilization assumption.

Age Difference

Compare two birth dates in calendar years, months and days, with an exact day count and explicit end-of-month handling.

Parallel Resistor

Calculate equivalent resistance for up to 100 parallel branches, with optional voltage-based branch current and power checks.

Scrap Silver

Estimate fine-silver mass, metal value and a buyer payout from supplied weight, purity and price; no live silver quote is loaded.

Z-Score

Standardize a numeric observation using an independently supplied mean and positive standard deviation, with signed distance interpretation.

Circumference

Find a circle’s circumference from radius or diameter, or recover radius and diameter from a known perimeter, with area as supporting output.

Pounds and Ounces Converter

Convert avoirdupois pounds, mass ounces and grams, including a normalized pounds-plus-ounces result; fluid and troy ounces are excluded.

Pizza Party

Estimate whole pizzas, slice coverage and pizza cost from your guest count, appetite assumptions, cut size and optional extra allowance.

Length Conversion

Convert millimetres, centimetres, metres, kilometres, inches, feet, yards and international miles with an explicit unit selector.

Energy

Electricity Usage

Estimate appliance kWh and usage cost from power, runtime, device count, duty cycle and a supplied flat electricity price.

Eigenvalue

Find eigenvalues of a numeric 2×2 real matrix, with real unit eigenvectors or a labeled complex conjugate pair and trace checks.

Percent Error

Compare a measured value with a nonzero reference using absolute percent error, signed relative error and the underlying difference.

Midpoint

Find a two-dimensional Cartesian segment midpoint, full distance and half-distance from two coordinate pairs, with clear geometric scope.

Dew Point

Estimate liquid-water dew point from air temperature and relative humidity, with Celsius/Fahrenheit output and an explicit 0–50°C model boundary.

Lottery Annuity

Model an escalating lottery payout schedule from supplied total, payment count and assumptions, including discounted value without a live cash-option quote.

Feet and Inches

Add or subtract two mixed feet-and-inches lengths, with normalized signed output, total inches, decimal feet and metres.

Long Division

Divide written finite decimals with exact scaled-integer arithmetic, visible fractional steps, repeating-digit notation and a bounded decimal expansion.

Permutation and Combination

Count selections or ordered arrangements of distinct items without replacement using exact integer arithmetic for 0 ≤ r ≤ n ≤ 1000.

Logarithm

Calculate a real logarithm with any positive base other than one, plus natural/base-ten values and an exponent reconstruction check.

Trip Fuel Cost

Estimate fuel quantity and trip cost using supplied distance, economy, fuel price and trip count, with explicit US or imperial gallon choices.

Big Number

Add, subtract, multiply or divide signed integers up to 500 digits without floating-point rounding, with a labeled integer quotient and remainder.

Matrix Multiplication

Multiply numeric matrices up to 8×8 with dimension checks, row-by-column results, worked examples and clear floating-point limits.

Decimal to Fraction

Convert a written finite decimal to an exact reduced fraction and mixed number using integer arithmetic, with sign and precision checks.

Blown Insulation

Estimate whole blown-insulation bags using measured area, actual product-label coverage, supplied allowance and material-only bag price.

Euler’s Method

Apply explicit Euler steps to y′=a·x+b·y+c with initial conditions, signed step size, final estimate and bounded iteration preview.

Log Weight

Estimate an ideal tapered log’s volume and mass from two measured end diameters, length and independently supplied bulk density.

Roman Numeral

Convert numbers, canonical Roman numerals and real Gregorian date components with explicit notation limits and labeled date order.

Engineering

Prop Slip

Calculate apparent propeller slip from matched engine RPM, reduction ratio, nominal pitch and measured mph, preserving negative results.

Engineering

RC Filter

Calculate ideal first-order RC cutoff, time constant and low-pass or high-pass amplitude at a supplied frequency with unit checks.

Probability

Calculate two-event union, intersection, neither and conditional probabilities using explicit independence or a supplied feasible overlap.

Target Heart Rate

Explore adult age-predicted maximum heart rate and supplied percentage references, with clear limits on individual interpretation.

Pension Benefit

Calculate a supplied final-salary pension accrual scenario from pensionable pay, credited service, accrual denominator and adjustment.

Grams to mL

Convert grams to milliliters or reverse using your supplied material density, with explicit units and no universal water assumption.

Siding Course

Count whole siding boards by rectangular wall courses, stock length, exposed height and supplied allowance, without offcut optimization.

Difference Quotient

Calculate a quadratic difference quotient and derivative limit from numeric coefficients, x and nonzero h with cancellation checks.

Odds and Risk Ratio

Compare observed event risks, risk ratio, odds ratio and percentage-point difference from two-group counts, with study-design limits.

Media

Time-Lapse

Plan fixed-interval time-lapse capture count, clip duration and speed-up from a recording window, capture interval and playback fps.

Mileage Reimbursement

Calculate recorded mileage and supplied-rate reimbursement from odometer readings in miles or kilometers, without automatic tax rates.

Sport

Draw Length

Convert measured nock-to-grip-pivot distance to ATA-convention draw length in inches and centimeters, without prescribing equipment.

Cardiac Output

Check educational heart-rate times stroke-volume arithmetic and optional supplied-BSA cardiac index, without diagnosis or ranges.

Option Profit

Calculate purchased call or put expiry profit, payoff and fee-inclusive break-even from supplied prices, contract size and fees.

Drywall

Estimate whole drywall sheets from wall and ceiling area, measured openings, panel size and an explicit allowance, with net-area checks.

0–60

Estimate time from rest to a supplied speed using constant acceleration, with mph or km/h inputs and clearly labeled distance and gravity checks.

Energy

Watt Hour

Calculate watt-hours from supplied watts and operating hours, then compare kWh and joules without assuming battery capacity or efficiency.

KD

Calculate kills divided by deaths, handle zero deaths explicitly and estimate additional kills for a supplied K/D target with no future deaths.

Deck Board

Estimate straight deck-board rows and stock pieces from actual board width, supplied gap and stock length, with an explicit ordering allowance.

Plate Rolling

Calculate an illustrative developed plate length from inside radius, thickness, supplied neutral-axis factor, arc angle and process allowance.

Running Record

Calculate reading accuracy, error ratio, self-correction ratio and optional correct words per minute from supplied running-record tallies.

Timecode

Add or subtract HH:MM:SS:FF durations at supported integer non-drop-frame rates, with signed frame counts and elapsed-second checks.

Cow Gestation

Plan a cattle calving date from a known service date and an adjustable whole-day interval, with the 283-day convention clearly disclosed.

Rim Offset

Compare nominal wheel width and signed offset to calculate inward and outward rim-edge movement in millimetres, without claiming vehicle fitment.

Correlation Coefficient

Calculate Pearson r from matched X and Y lists, with pair-count and mean checks, explicit constant-list errors and no causal or significance claims.

Speed

Solve average speed, distance or elapsed time using kilometres and hours, with mph, metres per second and feet per second conversion checks.

TV Mounting Height

Plan screen center, edges and a supplied bracket reference height from seated eye height and actual screen height, without universal mounting claims.

Wire Length

Calculate cable-route and individual-conductor lengths from measured paths, conductor count, supplied slack and a separate ordering allowance.

Gear Ratio

Calculate road speed from engine RPM or RPM from speed using supplied transmission ratio, final drive and rolling tyre diameter, without slip assumptions.

Christmas Tree Light

Estimate additional Christmas light strands from tree height, your decorative density, product light count and existing lights, without wiring assumptions.

OPS

Calculate unadjusted baseball OPS from official at-bats, hits, walks, hit-by-pitch, sacrifice flies and extra-base hits, with component checks.

Binomial Distribution

Calculate exact, at-most and at-least binomial probabilities for up to 500 independent trials, with decimal success probability and endpoint handling.

Octagon

Calculate regular-octagon area, perimeter, apothem and side-to-side or vertex-to-vertex spans from a positive side length in consistent units.

Winrate

Calculate recorded win rate with an explicit draw denominator and estimate consecutive wins needed for a target, including impossible 100% cases.

Horsepower

Calculate shaft horsepower and kilowatts from measured torque and matching rpm, with separate mechanical and metric horsepower definitions.

Interest Rate Cap

Calculate an illustrative interest-rate cap period payout from supplied notional, index, strike and day count, without market premium estimates.

Halfway Point Between Two Cities

Find a spherical geographic halfway point from two latitude and longitude pairs, with explicit limits for road distance and driving-time searches.

Cake Pricing

Price a cake from ingredients, packaging, labor, overhead and selling fees, with a target profit margin calculated from the final selling price.

Sheep Gestation

Estimate a sheep lambing planning date and reference window from a known mating date, with clear limits for pregnancy confirmation and breed variation.

Boolean Algebra

Evaluate Boolean expressions with NOT, AND, XOR and OR, generate all truth-table rows for up to four variables, and check tautology or contradiction.

Megawatt

Convert a supplied power value between watts, kilowatts, megawatts and gigawatts while keeping power separate from watt-hour energy calculations.

Substitution

Solve a two-variable linear system from six coefficients, check both residuals, and identify cases without a numerically stable unique solution.

Cap Rate

Calculate a property capitalization rate from annual operating income, expenses and supplied property value, with debt-service and valuation limits.

Swim Time Converter

Convert swim times using distance ratios and your explicit course factor, with yards/metres handling and clear SCY, SCM and LCM performance limits.

CPM

Calculate campaign CPM from spend and impressions, or estimate impressions from a supplied constant CPM, with clear campaign and measurement definitions.

Fence Cost Estimator

Estimate fence project cost from measured run length, supplied material and labor rates, gate costs and a separate material allowance.

Subwoofer Case

Calculate a rectangular subwoofer enclosure’s net air volume from external dimensions, panel thickness and supplied internal displacement.

Acres per Hour

Estimate farm-machine field capacity from working width, ground speed and supplied efficiency, plus operating hours for a chosen field area.

N·m to ft-lb Converter

Convert signed torque between newton metres and pound-force feet, with explicit unit factors and limits for fastener and energy interpretations.

Epoxy Resin Calculator

Estimate mixed epoxy, resin and hardener volumes for a rectangular layer using centimetres, millimetres, supplier volume ratio and an explicit allowance.

Molarity Calculator

Calculate molarity from grams or moles, required solute mass, or stock volume for dilution using molar mass and final solution volume in millilitres.

Garage Door Spring Calculator

Estimate ideal static garage-door balancing torque from verified weight force, effective drum moment arm and equally sharing springs, with clear limits.

Lawn Mowing Cost Calculator

Estimate lawn mowing labor time, price per visit and repeat-visit cost from measured lawn area, effective productivity, hourly charge and fixed visit cost.

1/4 Mile Calculator

Estimate quarter-mile elapsed time and trap speed from race weight, effective horsepower and disclosed empirical coefficients, with performance limits.

Firewood Calculator

Calculate full-cord equivalents, cubic feet, cubic metres and indicative price from measured rectangular firewood stack dimensions and a full-cord rate.

Nether Portal Calculator

Convert Overworld and Nether X/Z coordinates using the standard 8:1 scale, with exact and lower integer targets and an unchanged Y reference.

ARV Calculator

Estimate indicative after-repair value from matching sold prices and floor areas, subject size, a supported adjustment and user-entered project costs.

Breastfeeding Calorie Calculator

Add the CDC general breastfeeding energy range to a known pre-pregnancy reference intake, with clear limits and no weight-loss or milk-output prediction.