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Enter your values, then click Calculate result.How this calculator helps
This ideal gas law calculator rearranges a single equation of state for four common unknowns. It is useful for an introductory gas problem with compatible known measurements and an explicitly ideal-gas assumption. The inputs use one coherent SI unit system, so the constant does not silently change between atmospheres, litres and pascals. Real-gas corrections, gas mixtures with reactions and equipment ratings require additional information beyond this model.
How to use it
- 1
Choose the unknown or identify the quantity required by your problem before entering measurements.
- 2
Convert each supplied measurement to the SI units printed beside its field. Keep the directional sign convention consistent throughout the problem.
- 3
Read the method and worked example, then click Calculate result. The saved result remains visible while you edit inputs.
- 4
Check the units, limiting case and reconstructed equation before copying the answer into a report or worksheet.
Formula and methodology
PV = nRT, with R = 8.31446261815324 J/(mol·K). Pressure is Pa, volume m³, amount mol and temperature K.
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 1 mol of ideal gas at 300 K in 0.025 m³, predicted absolute pressure is about 99,773.5514 Pa. Select Pressure and enter these known quantities. In Volume mode, the same pressure, amount and temperature reproduce 0.025 m³. If temperature doubles to 600 K while volume and amount stay fixed, pressure doubles. A temperature of 300 °C is not 300 K; it must first be converted to 573.15 K.
How to interpret your result
The selected unknown appears first and all four state variables appear below it. These values form one ideal-gas state in the supplied SI units. They do not establish a pressure-vessel rating, a safe heating procedure or a material compatibility conclusion. If a measured pressure differs, review temperature scale, pressure reference, vessel volume and whether a real-gas correction is required.
For different inputs or formulas, use Molarity Calculator; Molecular Weight Calculator; Density Mass Volume Calculator.
Related questions this calculator covers
- ideal gas law calculator
- pv nrt calculator
- gas pressure volume temperature calculator
Scenario comparison
| Scenario | What it shows |
|---|---|
| Fixed vessel | doubling kelvin temperature doubles pressure at fixed moles. |
| Expansion | doubling volume halves pressure at fixed temperature and moles. |
| Inverse check | each solve mode reconstructs the same state from three known variables. |
Common mistakes to avoid
- Using Celsius directly in an absolute-temperature equation.
- Entering litres into a cubic-metre field.
- Substituting gauge pressure for absolute pressure.
Calculate 1 × 8.31446261815324 × 300 / 0.025 independently and compare with the displayed pressure. Use that pressure to solve volume and recover 0.025 m³. Verify that PV and nRT are equal within rounding. Dimensional analysis gives Pa·m³ = J, matching mol × J/(mol·K) × K.
Authoritative reference. Method reference checked for this worksheet. The calculation and examples are independently implemented; read the specific scope and units above.What can affect the result?
Use absolute pressure
Absolute pressure is referenced to a vacuum. Gauge pressure is referenced to surrounding atmospheric pressure and must be converted using the relevant atmospheric value. A zero gauge reading therefore does not usually mean zero absolute pressure. The equation uses absolute pressure, and this worksheet requires it to be positive. It does not infer local atmospheric pressure from a location or a weather record.
Use kelvin for temperature
Temperature in the ideal-gas equation must be measured on an absolute scale. Convert Celsius by adding 273.15, and Fahrenheit by first converting to Celsius. Using a Celsius number directly distorts both proportional changes and inverse solutions. A negative Celsius temperature can be physically meaningful after conversion to positive kelvin; a zero or negative kelvin entry is outside this ideal-gas worksheet.
Volume is expressed in cubic metres
One litre equals 0.001 m³, while one millilitre equals 0.000001 m³. A vessel with 25 litres of internal gas volume uses 0.025 in the volume field. Do not substitute an external vessel dimension, liquid volume or a number in litres without conversion. The relevant gas volume and boundary must match the pressure and temperature measurements.
Amount means moles of particles
The n field is amount of substance in moles, not mass in grams and not a molecule count. Converting a gas mass to moles requires its appropriate molar mass. For an ideal mixture without reaction, total moles can enter the state equation, but separate partial-pressure questions need mixture composition. The calculator does not identify a gas or infer molar mass from a name.
When the ideal assumption can fail
The ideal relation omits intermolecular attractions and particle volume. Real gases can depart substantially from it at high pressure, low temperature or near condensation. A numerical answer with many digits is not proof that an actual gas behaves ideally. Assess the model’s applicability from suitable physical data or a compressibility factor before relying on it for quantitative laboratory or engineering interpretation.
Inversion and proportional checks
At fixed amount and temperature, doubling volume halves predicted pressure. At fixed pressure and amount, doubling absolute temperature doubles volume. The solve selector identifies which input is ignored because it is computed from the others. This avoids requiring a guessed unknown, but all known inputs must be positive. Reconstruct PV and nRT after an inverse calculation to check consistency within rounding.
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
Use only the disclosed input domains and model. Using Celsius directly in an absolute-temperature equation. Review the method-specific boundaries above and the linked source before interpreting a result. Calculations use browser floating-point arithmetic; displayed digits are not a measure of real-world certainty. Your entries stay on this device and are not submitted to a calculation server.
Sources and review information
Frequently asked questions
Can pressure be entered in atmospheres?＋
Convert to pascals before entering it; this page uses SI units throughout.
Can I type a Celsius temperature?＋
Convert it to kelvin first by adding 273.15.
Is gauge pressure acceptable?＋
Use absolute pressure, including the relevant atmospheric reference conversion.
Does it include real-gas compressibility?＋
No. It uses the ideal equation without a Z correction.
Which field is ignored when solving?＋
The selected unknown is computed from the other three fields.