About the Gas Law Calculator
What is the Gas Law Calculator?
The combined gas law links pressure, volume and temperature for a fixed amount of gas. It includes Boyle's law (constant T), Charles's law (constant P) and Gay-Lussac's law (constant V) as special cases.
Choose what to find and enter the initial state and the known final values. Temperatures are converted to kelvin automatically.
How to use the Gas Law Calculator
- Find (sample: Final volume V₂)
- Initial Pressure P₁ (kPa) (sample: 100)
- Initial Volume V₁ (L) (sample: 10)
- Initial Temperature T₁ (°C) (sample: 27)
- Final Pressure P₂ (kPa) (sample: 200)
- Final Volume V₂ (L) (sample: 5)
- Final Temperature T₂ (°C) (sample: 27)
- Press Solve the Combined Gas Law (results also refresh as you type). The result card shows the Result, along with Solved for, P × V ÷ T (constant) and Law.
Formula used
P₁V₁ ÷ T₁ = P₂V₂ ÷ T₂
- T = absolute temperature in kelvin (°C + 273.15)
Pressure and volume units cancel, so any consistent units work.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Find | Final volume V₂ |
| Initial Pressure P₁ (kPa) | 100 |
| Initial Volume V₁ (L) | 10 |
| Initial Temperature T₁ (°C) | 27 |
| Final Pressure P₂ (kPa) | 200 |
| Final Volume V₂ (L) | 5 |
| Final Temperature T₂ (°C) | 27 |
| Result | Value |
|---|---|
| Result | 5 L |
| Solved for | Final volume |
| P × V ÷ T (constant) | 3.3317 kPa·L/K |
| Law | P₁V₁ ÷ T₁ = P₂V₂ ÷ T₂ (temperatures in kelvin) |
Tips for using the Gas Law Calculator
- Always convert temperatures to kelvin – using °C gives wrong answers.
- Tyre pressure rises on a hot day because the volume is nearly fixed.