Charles Law Calculator

What Is Charles's Law?

Charles's law states that the volume of an ideal gas is directly proportional to its absolute temperature when pressure stays constant. Heating a balloon makes it expand; cooling it shrinks.

Charles's Law Formula

$$\frac{V_1}{T_1} = \frac{V_2}{T_2}$$

Temperatures must be in Kelvin. The calculator accepts Celsius and converts automatically:

$$T_K = T_{^\circ\text{C}} + 273.15$$

Rearrangements for each unknown:

$$V_2 = V_1 \cdot \frac{T_2}{T_1}, \quad T_2 = V_2 \cdot \frac{T_1}{V_1}$$

Example: 1 L of air at 20 °C heated to 47.15 °C (320.15 K) expands to about 1.1 L at constant pressure.

Frequently Asked Questions

Why must temperature be in Kelvin?

Charles's law uses absolute temperature. Celsius offsets would make ratios wrong at low temperatures. Always add 273.15 to Celsius before dividing volumes.

Does Charles's law apply to real gases?

It is accurate for ideal gases at moderate pressure and temperature. Real gases deviate near condensation or at very high pressure.

What stays constant in Charles's law?

Pressure and amount of gas (moles) must remain fixed. If pressure changes, combine Charles's law with Boyle's law or the ideal gas law.

Can volume be in liters or m³?

Yes, as long as V₁ and V₂ use the same unit. The ratio cancels units; only consistency matters.

What if temperature drops below 0 °C?

Enter negative Celsius values normally. The calculator converts to Kelvin. Physical gas volumes cannot reach absolute zero, but the math still applies above 0 K.

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What Is Charles's Law?

Charles's Law Formula

Frequently Asked Questions

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