Ideal gas law calculator

Calculate ideal-gas pressure with P = nRT/V using kelvin, cubic metres and moles.

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Amount (mol)

Absolute temperature (K)

More inputs and assumptions

Volume (m³)

Input mode

Answer

…

Ideal gas relation PV = nRT, using R = 8.31446261815324 J/(mol·K). Pressure mode uses cubic metres; amount mode converts litres to cubic metres by dividing by 1,000. Temperature and volume must be positive.

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Precision and calculation record

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Formula and assumptions

Uses R = 8.31446261815324 J/(mol K), derived from SI defining constants. Pressure is absolute, not gauge. The ideal model can fail for real gases at high density or near condensation.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Ideal gas law calculator

Uses R = 8.31446261815324 J/(mol K), derived from SI defining constants. Pressure is absolute, not gauge. The ideal model can fail for real gases at high density or near condensation.

Next: Pressure calculator

Next: Atoms to moles calculator

A worked example

Example inputs: amount (mol) = 1, absolute temperature (k) = 300, volume (m³) = 1. Pressure (Pa) = 2494.338785445972.

Before you use the result

Uses R = 8.31446261815324 J/(mol K), derived from SI defining constants. Pressure is absolute, not gauge. The ideal model can fail for real gases at high density or near condensation.

Example results for amount (mol)

These examples use Absolute temperature (K): 300; Volume (m³): 1; Input mode: Pressure from amount and volume. They are reference calculations, not recommended settings.

Amount (mol)	Pressure (Pa)
0.5	1247.16939272
1	2494.33878545
2	4988.67757089

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