Charles's Law Calculator (V₁/T₁ = V₂/T₂)
At constant pressure, gas volume is directly proportional to absolute temperature (in Kelvin). Find the new volume after a temperature change.
How to use this charles's law calculator
- 1Convert temperatures to Kelvin: K = °C + 273.15.
- 2Enter initial volume and temperature.
- 3Enter the final temperature.
- 4Example: 1 L at 0°C (273.15 K) heated to 100°C (373.15 K) → 1.366 L.
How it's calculated
V₁/T₁ = V₂/T₂ at constant pressure. V₂ = V₁ × T₂ ÷ T₁. Temperature MUST be in Kelvin.
About the Charles's Law Calculator
Charles's Law explains why hot-air balloons fly and why bread rises faster in a warm oven. The direct proportionality V ∝ T (in Kelvin) is elegant: double the absolute temperature, double the volume.
Practically: a car tyre at 20°C (293 K) vs 40°C (313 K) shows a 7% volume increase — which manifests as slightly higher tyre pressure since the tyre constrains volume. Temperature effects on gas are significant even at everyday temperature changes.
Frequently asked questions
Why must temperature be in Kelvin?
Kelvin is an absolute scale — 0 K is where molecular motion theoretically stops. Using Celsius would give nonsensical negative volumes. Charles's Law requires V=0 at T=0 K.
Everyday example?
Hot-air balloons: heating air increases its volume, lowering density below surrounding air, providing lift. A basketball left in a hot car expands; on a cold morning tyres look deflated.
Who was Jacques Charles?
Jacques Charles (1746–1823), a French physicist and balloonist, discovered this relationship in 1787 — the same year he made the first hydrogen balloon flight.