What is Charles's Law?

Charles's Law states that the volume of a gas is directly proportional to its absolute temperature when pressure is held constant. Mathematically: V1/T1 = V2/T2, where V is volume and T is temperature in Kelvin. This means if you heat a gas, it expands; if you cool it, it contracts. The law was formulated by French scientist Jacques Charles around 1780.

Why must temperature be in Kelvin for Charles's Law?

Charles's Law requires absolute temperature (Kelvin) because it's based on proportional relationships. At 0 Kelvin (absolute zero), gases theoretically have zero volume. Using Celsius or Fahrenheit would give incorrect results because these scales have arbitrary zero points. Always convert to Kelvin: K = °C + 273.15 or K = (°F - 32) × 5/9 + 273.15.

What are real-world applications of Charles's Law?

Charles's Law explains many everyday phenomena: hot air balloons rise because heated air expands and becomes less dense; a basketball left in cold weather deflates because the air inside contracts; bread dough rises when heated as gases expand; car tire pressure increases during summer driving. Any situation involving gas volume changes due to temperature uses this principle.

What happens to gas volume when temperature doubles?

According to Charles's Law, if you double the absolute temperature (in Kelvin) while keeping pressure constant, the volume also doubles. For example, heating a gas from 300K to 600K doubles its volume. However, doubling Celsius temperature does NOT double volume because Celsius isn't an absolute scale.

Does Charles's Law work for all gases?

Charles's Law is most accurate for ideal gases at low pressures and moderate temperatures. Real gases deviate from ideal behavior at very high pressures or very low temperatures (near liquefaction). For most practical applications with common gases at standard conditions, Charles's Law provides excellent approximations.

Math

Charles's Law Calculator

Calculate volume and temperature changes for a gas at constant pressure (V1/T1 = V2/T2).

Solve For

Initial Volume (V1)

Initial Temp (T1) [K]

Final Volume (V2)

Final Temp (T2) [K]

How to Use This Calculator

Enter Initial Conditions

Input the initial volume (V1) and initial temperature (T1) of your gas. Make sure to select the correct units - volume can be in liters, milliliters, or cubic meters, and temperature should be converted to Kelvin if you're entering Celsius or Fahrenheit.

Enter Known Final Condition

Enter either the final temperature (T2) to calculate final volume (V2), or enter the final volume (V2) to calculate final temperature (T2). The calculator will solve for the unknown variable using Charles's Law equation.

Calculate and Interpret

Click calculate to see your result. The calculator will show the missing value and may display the work shown, including temperature conversions to Kelvin. Verify that your answer makes physical sense (heating increases volume, cooling decreases volume).