Gay-Lussac's Law Calculator
Gay-Lussac's Law describes the direct relationship between the pressure and absolute temperature of a gas at constant volume. When the temperature of gas in a sealed rigid container rises, molecules collide with the walls more frequently and forcefully, increasing pressure. This law is critical for the safe design and operation of pressure vessels, autoclaves, aerosol cans, and gas cylinders. It also explains why fire departments warn against exposing pressurized cylinders to high heat. Enter any three values and solve for the fourth. Temperatures are entered and displayed in Celsius or Kelvin.
Gay-Lussac's Law formula
P1 / T1 = P2 / T2 (T must be in Kelvin)
P2 = P1 * T2 / T1
T2 = T1 * P2 / P1
T(K) = T(degC) + 273.15
Gay-Lussac's Law safety examples
- Aerosol can at 20 degC (293 K), 1 atm: at 100 degC (373 K), pressure rises to 1.27 atm.
- Oxygen cylinder at 2,000 psi and 20 degC: at 100 degC, pressure rises to about 2,546 psi.
- Car tire at 35 psi cold: after highway driving at 60 degC, pressure rises to about 39 psi.
- Pressure cooker: steam temperature reaches 120 degC (393 K), pressure is 2 atm (about 200 kPa).
Gay-Lussac's Law: frequently asked questions
What is Gay-Lussac's Law?
Gay-Lussac's Law states that at constant volume, the pressure of a fixed amount of gas is directly proportional to its absolute temperature: P1/T1 = P2/T2. Doubling the absolute temperature doubles the pressure. This explains why pressurized containers can explode when heated.
What is the difference between Gay-Lussac's Law and the other gas laws?
Boyle's Law: P and V at constant T. Charles' Law: V and T at constant P. Gay-Lussac's Law: P and T at constant V. All three are special cases of the ideal gas law PV = nRT. Gay-Lussac's Law specifically applies when volume is fixed (rigid containers, autoclaves, pressure vessels).
What are safety implications of Gay-Lussac's Law?
Aerosol cans, oxygen cylinders, and other pressurized containers obey Gay-Lussac's Law. If a sealed container at 1 atm and 20 degC (293 K) is heated to 200 degC (473 K), pressure rises to 1.61 atm - a 61% increase. Most aerosol cans are rated for 130 degC; exceeding this can cause rupture.
How does Gay-Lussac's Law apply to tires?
A car tire is approximately a constant-volume container. When tires heat up during driving (from 20 degC to 60 degC, i.e., 293 K to 333 K), pressure increases by about 14%. This is why tire pressures should be checked cold. Under-inflated cold tires will be even more under-inflated when heated.
What are practical applications in chemistry?
Gay-Lussac's Law is used in autoclave sterilization (heating steam in a sealed chamber increases both temperature and pressure), pressure cooker cooking, and the study of gas reactions at constant volume in bomb calorimeters where the heat of combustion is measured.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.