Gas Laws Calculator
Solve Boyle's, Charles's, Gay-Lussac's and the combined gas law for pressure, volume or temperature.
About the Gas Laws Calculator
For a fixed amount of an ideal gas, pressure × volume ÷ absolute temperature stays constant. Boyle's law (constant temperature): squeeze a gas to half the volume and its pressure doubles. Charles's law (constant pressure): volume grows in proportion to kelvin temperature. Gay-Lussac's law (constant volume): pressure rises with temperature, which is why aerosol cans warn against heat. Always use kelvin; pressure and volume can be in any units as long as they match.
The formula
P₁V₁ ÷ T₁ = P₂V₂ ÷ T₂ (T in kelvin = °C + 273.15)
Worked example
Example: Final volume = 1.22362
- Inputs: Law: Combined (P, V, T); Find: Final volume V₂; Temperatures in: °C; Initial pressure P₁: 110 kPa (any unit); Initial volume V₁: 2 L (any unit); Initial temperature T₁: 22; Final pressure P₂: 220 same unit as P₁; Final temperature T₂: 88.
- Formula: P₁V₁ ÷ T₁ = P₂V₂ ÷ T₂ (T in kelvin = °C + 273.15)
- Result: Final volume = 1.22362
Questions people ask
Why kelvin?
The laws are proportional to absolute temperature; 0 °C isn't zero energy.
Why must temperature be in kelvin?
The gas laws need absolute temperature: pressure and volume are proportional to T only when T is measured from absolute zero. Convert °C by adding 273.15.