In a sealed rigid container, pressure rises in proportion to absolute temperature. That is why aerosol cans warn against heating and why tyre pressure rises after a long drive.
How to use the Gay-Lussac’s Law Calculator
- Find
- Initial pressure p₁
- Initial temperature T₁
- Final temperature T₂
- Final pressure p₂
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose what to find and enter the known values.
Tips
- Use absolute temperature (K) in gas laws and efficiency formulas.
- Temperature differences are the same in K and °C.
- Heat = mass × specific heat × temperature change when no phase change occurs.
- Phase changes need latent heat at a constant temperature.
Common mistakes to avoid
- Using °C in pV = nRT.
- Forgetting latent heat during melting or boiling.
- Confusing heat capacity (J/K) with specific heat (J/(kg·K)).
Inputs explained
| Field | What to enter |
|---|---|
| Find | Choose one: Final pressure p₂, Final temperature T₂ |
| Initial pressure p₁ | Units: kPa, Pa, bar, atm, psi, MPa |
| Initial temperature T₁ | Units: K, °C, °F |
| Final temperature T₂ | Units: K, °C, °F |
| Final pressure p₂ | Units: kPa, Pa, bar, atm, psi, MPa |
What each result means
- Final pressure p₂ = [Initial pressure p₁]×[Final temperature T₂]÷[Initial temperature T₁]
- Final temperature T₂ = [Initial temperature T₁]×[Final pressure p₂]÷[Initial pressure p₁]
Example values
How the main result changes when Initial pressure p₁ changes and everything else stays at the example values above:
| Initial pressure p₁ (kPa) | Final pressure p₂ (kPa) |
|---|---|
| 110 | 121.257 |
| 165 | 181.8856 |
| 220 | 242.5141 |
| 275 | 303.1426 |
| 330 | 363.7711 |
| 440 | 485.0281 |
Formula
p₁/T₁ = p₂/T₂ (absolute temperatures)Worked example
Inputs — Find: Final pressure p₂; Initial pressure p₁: 220 kPa; Initial temperature T₁: 293.15 K; Final temperature T₂: 323.15 K.
Results — Final pressure p₂ = 242.51407 kPa.
Key terms
- Isochoric
- At constant volume.
Frequently asked questions
Why do tyre pressures rise when driving?
The air inside warms up at nearly constant volume.
Should I use gauge or absolute pressure?
Absolute pressure.
Why do aerosol cans explode when heated?
Pressure rises with temperature in the sealed can.
Who discovered this law?
Joseph Louis Gay-Lussac, around 1802.
What formula does the Gay-Lussac's Law Calculator use?
p₁/T₁ = p₂/T₂ (absolute temperatures).