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Ideal Gas Law Calculator

Updated Sep 2026 Used 0 times
Enter the amount of gas.
Enter the volume occupied by the gas.
Enter Kelvin, not degrees Celsius.

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Your result

Calculated ideal-gas pressure

Enter your values, then calculate to see a verified result.

Inputs usedReview the information used for this result.
Full calculation and sourcesUses R = 8.314462618 kPa·L·mol⁻¹·K⁻¹ and requires absolute temperature.

Versioned calculationFormula v1.0.0

Ideal-gas modelNIST/CODATA gas constantFormula v1.0.0

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Public verification recordFormula v1.0.0
Review scope
PV=nRT Pressure, Unit Normalization, Kelvin Boundary, Reference Atmosphere, And Real-gas Limitation
Review team
CalculatorGeek Algorithmic Team
Verified
2026-09-27
Next source review
2027-09-27
Automated fixtures
4 cases

Review method

Near-ambient reference, equivalent mmol/mL inputs, zero-volume rejection, zero-Kelvin rejection, and constant units reviewed separately.

Known limitations

  • Uses the ideal-gas equation and R = 8.314462618 kPa·L·mol⁻¹·K⁻¹.
  • Temperature must be absolute Kelvin and volume must be positive.
  • Real-gas deviation can matter at high pressure, low temperature, near condensation, or for strongly associating gases.

Primary sources

On this page

Ideal-gas formula

PV = nRT. Solving for pressure gives P = nRT/V. This implementation uses pressure in kPa, volume in litres, amount in mol, temperature in K, and R = 8.314462618 kPa·L·mol⁻¹·K⁻¹.

Continue with Connect gas amount to concentration or Use gas moles in a reaction for the next calculation.

Unit and temperature check

Kelvin is an absolute scale, so convert Celsius using K = °C + 273.15. Keep the gas volume in L so the selected gas constant produces kPa.

Real-gas limitations

Ideal behavior is an approximation. Pressure, temperature, molecular interactions, and proximity to phase changes can produce measurable deviations. Use an equation of state or measured data when those effects matter. For reaction amounts, continue to the Stoichiometry Calculator.

Frequently asked questions

Can I enter Celsius directly?

No. Convert to Kelvin by adding 273.15.

When is PV = nRT not enough?

Use a real-gas equation of state or measured data when pressure is high, temperature is low, or the gas is near a phase change.

Sources

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