Your result
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Enter your values, then click Calculate result.How this calculator helps
Calculate equivalent resistance for up to 100 parallel branches, with optional voltage-based branch current and power checks. Write resistance values separated by commas, spaces or semicolons. All values use ohms. Convert 2.2 kΩ to 2200 before entering it; unit suffixes and expressions are not parsed. The list accepts one through one hundred positive finite values, each no greater than 10¹² Ω. Every listed value represents a complete branch directly across the same pair of circuit nodes.
How to use it
- 1
Choose the correct input basis for parallel resistor calculator and enter the values described below. The demonstration defaults are examples, not independently verified personal measurements.
- 2
Review conductance adds before submitting. Match the selected units and roles to the original source record, including any signs or percentage conventions.
- 3
Click Calculate result to submit the current inputs. Editing a field preserves the previous submitted output until you calculate again; the status message identifies that pending change.
- 4
Compare the labeled result with the worked example and independent verification checks. Review component reality before copying it into another worksheet.
Formula and methodology
1/Rₑq = Σ(1/Rᵢ). With supplied voltage V: branch current Iᵢ = V/Rᵢ, branch power Pᵢ = V²/Rᵢ, total current = V/Rₑq.
The calculator applies the displayed arithmetic to the values entered on this device. It does not silently load a local tax rate, currency conversion or commercial assumption.
Worked calculation example
For 100 Ω and 200 Ω in parallel, conductance is 0.01 + 0.005 = 0.015 siemens, so equivalent resistance is 66.666667 Ω. At 12 V, branch currents are 0.12 A and 0.06 A. Their 0.18 A sum also equals 12/66.666667.
How to interpret your result
Leave voltage blank when you only want resistance. Supplying a nonnegative voltage enables ideal branch current and power arithmetic. These extra rows depend on the supplied voltage remaining across every branch. A real source can sag under load, and a component’s actual resistance can change with temperature. Use measured values or specified conditions when a numerical comparison matters.
For different inputs or formulas, use Ohm’s Law, Watt and Ampere Calculator; RC Filter Calculator.
Related questions this calculator covers
- parallel resistor calculator
Scenario comparison
| Scenario | What it shows |
|---|---|
| Equal pair | two 100 Ω branches give 50 Ω. |
| Single branch | 220 Ω stays 220 Ω. |
| Added path | adding a positive branch reduces equivalent resistance. |
Common mistakes to avoid
- Adding branch resistances as if the parts were in series.
- Entering kΩ values without multiplying by one thousand.
- Treating ideal computed power as component-rating approval.
Check two branches with R₁R₂/(R₁+R₂), then compare the answer with the reciprocal-sum output. With voltage supplied, sum all branch currents and compare with total current. For equal branches, divide one resistance by the branch count. None of these arithmetic checks verifies the wiring or the real source voltage.
Authoritative reference. Method references reviewed on 5 October 2026. SolvePilot supplies the original examples and bounded browser implementation. Review by Mohammad Qasim covers editorial scope and arithmetic, not individual professional approval. The cited reference provides method or unit context rather than certifying the entered measurements or assumptions.What can affect the result?
Enter separate branches
Write resistance values separated by commas, spaces or semicolons. All values use ohms. Convert 2.2 kΩ to 2200 before entering it; unit suffixes and expressions are not parsed. The list accepts one through one hundred positive finite values, each no greater than 10¹² Ω. Every listed value represents a complete branch directly across the same pair of circuit nodes.
Conductance adds
Parallel branches share voltage, so their currents add. Conductance is the reciprocal of resistance, making the reciprocal-sum formula appropriate. For two branches, the familiar product-over-sum shortcut gives the same answer. This implementation scales the reciprocal sum by the smallest branch value to avoid avoidable reciprocal overflow. The equivalent resistance must be no greater than the smallest individual resistance.
Optional voltage
Leave voltage blank when you only want resistance. Supplying a nonnegative voltage enables ideal branch current and power arithmetic. These extra rows depend on the supplied voltage remaining across every branch. A real source can sag under load, and a component’s actual resistance can change with temperature. Use measured values or specified conditions when a numerical comparison matters.
Series and mixed networks
Adding resistance values directly describes series elements, not parallel branches. For a mixed network, simplify a genuine series or parallel subgroup first, then enter its equivalent only if the resulting topology really matches this page. The tool does not inspect a diagram, choose nodes or solve arbitrary bridge circuits. Misidentifying the wiring can produce a mathematically correct number for the wrong circuit.
Component reality
Ideal resistance and calculated power do not select a resistor rating or approve a circuit. Tolerance, ambient temperature, voltage limits and derating influence the physical parts. A zero-ohm branch would short the ideal network and is rejected rather than represented as an ordinary resistor. Negative resistance and complex AC impedance are outside scope. Extremely small displayed quantities use scientific notation to preserve a nonzero result.
Privacy and browser processing
Values entered on this page are processed in the current browser session. SolvePilot does not require an account and does not receive the values entered into the calculator. Refreshing or closing the page clears the working values unless the browser itself restores a previous session. Avoid entering identifying or account information because the calculation needs summary values only.
Accuracy and verification
Accuracy depends first on input quality. Confirm definitions, scales, dates and source information before entering a value. Keep an independent record of any result used for planning because this page does not create an official statement or retain a calculation history.
Limits of this estimate
Ideal resistance and calculated power do not select a resistor rating or approve a circuit. Tolerance, ambient temperature, voltage limits and derating influence the physical parts. A zero-ohm branch would short the ideal network and is rejected rather than represented as an ordinary resistor. Negative resistance and complex AC impedance are outside scope. Extremely small displayed quantities use scientific notation to preserve a nonzero result. Strictly positive numeric inputs must be at least 0.000000000001; values below that supported floor are rejected.
Sources and review information
Frequently asked questions
Can I enter kilohms?＋
Convert to ohms first. A 4.7 kΩ resistor is entered as 4700, while 4700Ω text is rejected because the list expects numeric values.
Why is the answer smaller than each resistor?＋
Each added positive parallel branch provides another current path. The sum of conductances increases, so its reciprocal resistance decreases.
Does a blank voltage mean zero volts?＋
No. Blank voltage omits current and power; entering zero explicitly computes zero current and power.
Can it solve capacitors or AC impedance?＋
No. This worksheet uses positive real ideal resistor values, not frequency-dependent complex impedances.
Can I use one branch?＋
Yes. Equivalent resistance equals that one branch value, which is a useful basic check.