Gases expand when heated and compress under pressure. The combined law handles both effects at once.
How to use the Combined Gas Law Calculator
- Initial pressure
- Initial volume
- Initial temperature
- Final pressure
- Final temperature
Results update as you type, and every field accepts the units shown in its menu.
How it works
Temperatures are converted to kelvin, then the starting volume is scaled by the pressure and temperature ratios.
Inputs explained
| Field | What to enter |
|---|---|
| Initial pressure | Units: Pa, kPa, MPa, bar, atm, psi … |
| Initial volume | Units: L, mL, m³ |
| Initial temperature | Units: K, °C, °F |
| Final pressure | Units: Pa, kPa, MPa, bar, atm, psi … |
| Final temperature | Units: K, °C, °F |
Example values
How the main result changes when Initial pressure changes and everything else stays at the example values above:
| Initial pressure (Pa) | Final volume (L) |
|---|---|
| 50,662.5 | 0.6364 |
| 75,993.75 | 0.9547 |
| 101,325 | 1.2729 |
| 126,656.25 | 1.5911 |
| 151,987.5 | 1.9093 |
| 202,650 | 2.5458 |
Formula
V₂ = V₁ × (P₁ ÷ P₂) × (T₂ ÷ T₁)Worked example
Inputs — Initial pressure: 101,325 Pa; Initial volume: 2 L; Initial temperature: 293.15 K; Final pressure: 202,650 Pa; Final temperature: 373.15 K.
Results — Final volume = 1.2729 L.
Frequently asked questions
When does this law apply?
For a fixed amount of ideal gas.
What if only temperature changes?
Set P₂ equal to P₁ and it becomes Charles’s law.
What formula does the Combined Gas Law Calculator use?
V₂ = V₁ × (P₁ ÷ P₂) × (T₂ ÷ T₁).