Charles's law says that at constant pressure, the volume of a fixed amount of gas is proportional to its absolute temperature. Heat a gas from 300 K to 600 K and its volume doubles.
Enter the temperatures in °C — the calculator converts them to kelvin, which the law needs. Using Celsius directly would give the wrong answer.
| Initial volume (V₁) | 2 L |
| Initial temperature (T₁) | 27 °C |
| Final temperature (T₂) | 127 °C |
| Final volume V₂ (L) | 2.66633 |
| Change in volume (L) | 0.666333 |
| T₁ in kelvin | 300.15 |
| T₂ in kelvin | 400.15 |
2 L of gas expands to 2.66633 L (300 K → 400 K).
Try this example →| Initial volume (V₁) | 3 L |
| Initial temperature (T₁) | 25 °C |
| Final temperature (T₂) | -18 °C |
| Final volume V₂ (L) | 2.56733 |
| Change in volume (L) | -0.432668 |
| T₁ in kelvin | 298.15 |
| T₂ in kelvin | 255.15 |
A 3 L balloon shrinks to 2.56733 L at −18 °C.
Try this example →At constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature.
Volume is proportional to absolute temperature; 0 °C is not zero temperature, so ratios in °C are meaningless.
V₁/T₁ = V₂/T₂.
Pressure and the amount of gas.