Charles's Law (V₁/T₁ = V₂/T₂)

Constant P: volume scales linearly with absolute temperature.

Inputs

Result

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How to use this calculator

  • Enter V₁, T₁, T₂.
  • Read V₂.

About this calculator

Charles's Law (1787): at constant pressure, gas volume scales linearly with absolute temperature. Heating doubles V if you double K (not °C!). Hot air balloons rise because heated air expands → less dense than surrounding air. Refrigerators exploit the opposite: cold compressed gas absorbs heat as it expands.

Frequently asked

Why Kelvin?+
Doubles when you double K (proportional). Celsius doesn't work — 200°C / 100°C ≠ 2× the volume effect (need 473 K / 373 K = 1.27× ratio).
Hot air balloon physics?+
Heat air → expands → density drops → buoyancy lifts. Same mass spread over more volume.
Refrigerator?+
Compress (heat), let outside, expand (cool), absorb heat from food. Reverse Carnot cycle.
Constant pressure assumption?+
Yes — open container or balloon. Sealed → use combined gas law (changes both P and V).
Volume at 0 K?+
Linear extrapolation hits V = 0 — mathematically. Physically gas liquefies / freezes well before then.

Related calculators

Ideal Gas Law (PV = nRT)
Solve for any of P, V, n, T given the other three. R = 8.314 J/(mol·K).
Boyle's Law (P₁V₁ = P₂V₂)
Constant T, constant n: pressure × volume = constant.
Avogadro's Law (V₁/n₁ = V₂/n₂)
At constant T, P: volume scales with number of moles.
Combined Gas Law (P₁V₁/T₁ = P₂V₂/T₂)
When n is constant, all of P, V, T can change. Solve for any one.
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