ChemBench

Gay-Lussac's Law Calculator

Heat a sealed container, pressure climbs.

Initial pressure (atm)

Initial temperature (K)

Final temperature (K)

Final pressure

1.167 atm

P₁/T₁ = P₂/T₂

What you entered

Initial pressure (atm): 1Initial temperature (K): 300Final temperature (K): 350

1
P₂ = P₁T₂ ÷ T₁
(1 × 350) ÷ 300= 1.1667

Result

Final pressure: 1.167 atm

Heating this fixed-volume gas to 350K raises pressure to 1.167 atm.

Gay-Lussac's law: pressure against temperature at fixed volume

P1/T1 = P2/T2, with temperature in kelvin. Heating a sealed rigid container raises the pressure proportionally.

Initial pressure	Initial temperature	New temperature	New pressure
1 atm	273.15 K (0 C)	546.30 K	2.0000 atm
1 atm	273.15 K (0 C)	373.15 K (100 C)	1.3661 atm
1 atm	293.15 K (20 C)	373.15 K (100 C)	1.2729 atm
2 atm	300 K	450 K	3.0000 atm
3 atm	298.15 K (25 C)	323.15 K (50 C)	3.2516 atm

This is the law behind warnings not to leave aerosol cans in a hot car: a jump from 20 C to 100 C raises the internal pressure by more than a quarter.

Pressure tracks temperature in a fixed volume

When a gas can't expand, raising its temperature forces its pressure up proportionally — this is why aerosol cans warn against heat exposure, and why tire pressure rises on a hot day.

A safety-relevant law

Understanding this relationship is why pressure vessels have temperature limits — a sealed rigid container heated enough can build pressure well past its rated capacity.

Frequently asked questions

A sealed gas cylinder reads 30 psi at 20°C — what will the pressure be at 50°C?

Convert to Kelvin: T1 = 293 K, T2 = 323 K. P2 = P1 × T2/T1 = 30 × 323/293 = 33.1 psi.

How is Gay-Lussac's law different from Charles's law?

Both link temperature to another gas property. Charles's law tracks volume changes at constant pressure (flexible container). Gay-Lussac's law tracks pressure changes at constant volume (rigid container). Use the Charles's law calculator for expandable systems.

Why do tires lose pressure in winter?

Cold temperatures lower air pressure inside the tire per Gay-Lussac's law. A tire at 35 psi in 30°C summer heat drops to about 32 psi at 0°C — roughly 1 psi lost per 5.5°C temperature drop.