Charles' Law Calculator

Charles' Law Calculator lets you solve for any variable in the Charles' Law equation — the relationship between volume and temperature of an ideal gas at constant pressure. Enter three known values — Initial Volume (V₁), Initial Temperature (T₁), and either Final Volume (V₂) or Final Temperature (T₂) — and the calculator solves for the missing fourth. Temperatures can be entered in Celsius, Kelvin, or Fahrenheit, and volumes in liters or cubic meters. Also try the Heat Loss Calculator.

Choose which variable you want to calculate.

Volume of the gas before the temperature change.

Temperature of the gas before the change. Must be above absolute zero.

Volume of the gas after the temperature change. Leave blank if solving for V₂.

Temperature of the gas after the change. Leave blank if solving for T₂.

Results

Calculated Result

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T₁ in Kelvin

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T₂ in Kelvin

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V/T Ratio (constant)

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Volume Change

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Frequently Asked Questions

What is Charles' Law?

Charles' Law states that the volume of a fixed amount of gas at constant pressure is directly proportional to its absolute temperature (in Kelvin). In other words, if you heat a gas, it expands; if you cool it, it contracts. The relationship is expressed as V₁/T₁ = V₂/T₂. See also our Heat Capacity Calculator.

When was Charles' Law discovered?

Charles' Law was first formulated by French physicist Jacques Charles around 1787, based on his experiments with gases and temperature. It was later published by Joseph Louis Gay-Lussac in 1802, who credited Charles for the original discovery.

How can I find T₂ using the Charles' Law equation?

To find the final temperature T₂, rearrange the formula: T₂ = (T₁ × V₂) / V₁. Make sure T₁ is in Kelvin (add 273.15 to Celsius). Once you calculate T₂ in Kelvin, convert back to your desired temperature unit if needed.

Why must temperature be in Kelvin for Charles' Law?

Charles' Law requires absolute temperature because the law is based on the proportional relationship between volume and temperature. Celsius and Fahrenheit scales can produce zero or negative values, which would make the ratios mathematically incorrect. Kelvin starts at absolute zero (−273.15°C), ensuring all temperature values are positive and proportional. You might also find our calculate Boiling Point Elevation useful.

What is the initial volume if a gas was heated from 270°C to 342°C and its final volume is 1 L?

Convert to Kelvin: T₁ = 270 + 273.15 = 543.15 K, T₂ = 342 + 273.15 = 615.15 K. Using V₁ = (V₂ × T₁) / T₂ = (1 × 543.15) / 615.15 ≈ 0.883 L. So the initial volume was approximately 0.883 liters.

What are real-life applications of Charles' Law?

Charles' Law explains many everyday phenomena: hot air balloons rise because heating the air inside increases its volume and reduces its density; car tires can over-inflate in summer heat; bread dough rises in a warm oven as gas bubbles expand; and liquid nitrogen cooling causes objects to shrink noticeably.

What are the limitations of Charles' Law?

Charles' Law applies only to ideal gases under constant pressure and assumes no change in the amount of gas. It breaks down at very high pressures, very low temperatures (near absolute zero), or when the gas is close to liquefying. Real gases deviate from the law more significantly under extreme conditions.

How is Charles' Law different from Boyle's Law and Gay-Lussac's Law?

Charles' Law relates volume and temperature at constant pressure (V ∝ T). Boyle's Law relates volume and pressure at constant temperature (V ∝ 1/P). Gay-Lussac's Law relates pressure and temperature at constant volume (P ∝ T). Together, these three laws combine into the combined gas law and ultimately the ideal gas law (PV = nRT).