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Gas states · Chemistry

Combined Gas Law Calculator

Calculate a final gas volume when pressure and absolute temperature change at constant amount of gas.

Formula shown Runs locally Reviewed Aug 11, 2026
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Equation guide

Fixed amount of ideal gas between two equilibrium states

Combined gas law

P₁V₁/T₁ = P₂V₂/T₂

Final volume

V₂ = P₁V₁T₂/(P₂T₁)
Gas-state calculator

Solve final volume V₂

P₁ and P₂ must use the same pressure unit. Temperatures must be absolute values in kelvins; V₂ is returned in the unit used for V₁.

P₁V₁/T₁=P₂V₂/T₂

The final gas volume will appear here.

Using the model

Symbols, assumptions and limitations

Interpretation notes

Temperatures must be in kelvins. P₁ and P₂ must be absolute pressures expressed in the same unit, and the result uses the same volume unit as V₁. The amount of gas is fixed and ideal-gas behavior is assumed.

Worked examples

See the method in practice

01

Balanced changes

Doubling both pressure and absolute temperature leaves volume unchanged.

02

Heating at fixed pressure

At constant pressure, volume is directly proportional to absolute temperature.

Questions

Frequently asked

Can I enter Celsius?

No. Convert every temperature to kelvins first.

Must pressure be in pascals?

No, provided P1 and P2 use the same absolute-pressure unit.

Sources & review

Equations and examples are checked against the references below. Results are educational and should be independently verified for safety-critical work.

OpenStax Chemistry — gas law relationships

Written by the STEM Hub editorial team · Reviewed August 11, 2026 · Review methodology