Apply the combined gas law to relate pressure, volume and temperature between two states.
The combined gas law follows from the ideal gas law with a fixed amount of gas. Temperatures must be absolute — using Celsius gives badly wrong answers because the ratio is meaningless without a true zero. Forgetting to convert to kelvin is the most common error in gas calculations, and it produces results that can even change sign.
Gas Law
p₁V₁ ÷ T₁ = p₂V₂ ÷ T₂, with temperatures in kelvin
p₁V₁ ÷ T₁ = p₂V₂ ÷ T₂, with temperatures in kelvin The combined gas law follows from the ideal gas law with a fixed amount of gas. Temperatures must be absolute — using Celsius gives badly wrong answers because the ratio is meaningless without a true zero.
Forgetting to convert to kelvin is the most common error in gas calculations, and it produces results that can even change sign.
This calculator takes 5 inputs: Initial pressure, Initial volume, Initial temperature, Final pressure, Final temperature. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.