Combined Gas Law Calculator Australia 2026-27

GlobalCalc

Inputs

Initial pressure (P₁)

kPa

Initial volume (V₁)

Initial temperature (T₁)

°C

Final pressure (P₂)

kPa

Final temperature (T₂)

°C

Results update as you type

Results

Final volume (V₂)

1.1023 L

Volume ratio V₂ ÷ V₁—

Amount of gas (mol, ideal)—

T₁ in kelvin—

T₂ in kelvin—

Reviewed September 2026. Chemistry is the same in every country: SI and laboratory units throughout.

All calculations run 100% in your browser. The calculator code does not submit your figures to GlobalCalc to obtain a result.

About combined gas law

Method

How the combined gas law calculator works

For a fixed amount of gas, P V ÷ T is constant, so P₁V₁ ÷ T₁ = P₂V₂ ÷ T₂. Enter the starting pressure, volume and temperature and the final pressure and temperature to get the final volume. Temperatures must be absolute: the calculator converts from °C to kelvin. Leave pressure unchanged and it is Charles's law; leave temperature unchanged and it is Boyle's.

Formula: V₂ = P₁ V₁ T₂ ÷ (P₂ T₁), T in kelvin

Data

Worked examples

Inputs	Final volume (V₂)	Note
2 L at 101.3 kPa, 20 °C → 202.6 kPa, 50 °C	1.1023 L	1.10 L
Boyle: 2 L at 100 kPa → 400 kPa, same temperature	0.5 L	0.5 L
Charles: 1 L at 0 °C → 100 °C, same pressure	1.3661 L	1.366 L

FAQ

Frequently asked questions

Why must temperature be in kelvin?

Because volume is proportional to absolute temperature. Doubling from 10 °C to 20 °C is not doubling the temperature; 283 K to 293 K is a 3.5% rise.

Which gas laws does this cover?

Boyle (constant T), Charles (constant P) and Gay-Lussac (constant V) are all special cases of P V ÷ T = constant.

What about the amount of gas changing?

Then use the ideal gas law P V = n R T — see the ideal-gas-law calculator.

How ideal are real gases?

Air, nitrogen and helium at ordinary pressures are within about 1% of ideal. Near liquefaction or above tens of atmospheres, deviations grow.

Sources

Where these figures come from

IUPAC — Standard atomic weights (2021 conventional values) — the molar-mass table
NIST — CODATA 2018 fundamental physical constants — Avogadro constant, gas constant, speed of light
NIST Chemistry WebBook — thermochemical data
CSIRO — Australia's national science agency

Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.