What is the Charles' Law Calculator?
Charles' law states that for a fixed amount of gas at constant pressure, volume and absolute temperature are directly proportional: V₁/T₁ = V₂/T₂. Enter any three of initial volume, initial temperature, final volume, and final temperature — this calculator solves the fourth. Supports liters and milliliters for volume and kelvin or Celsius for temperature (converted to kelvin internally). Also shows V₂/V₁ and T₂/T₁ ratios. Runs instantly in your browser with no signup.
How to use the Charles' Law Calculator
- Choose which variable to solve: V₂, T₂, V₁, or T₁.
- Enter the three known values.
- Select volume and temperature units.
- Read the solved value and volume/temperature ratios.
- Copy the summary for homework or lab notes.
Common use cases
- Finding final volume when a gas is heated from 273 K to 546 K at constant P
- Calculating final temperature when volume halves isobarically
- Predicting volume change from 0 °C to 100 °C in a sealed syringe
Frequently asked questions
- What is Charles' law?
- V₁/T₁ = V₂/T₂ at constant pressure and fixed moles of gas. If absolute temperature doubles, volume doubles.
- Why must temperature be in kelvin?
- Charles' law uses absolute temperature. The calculator accepts °C and converts to kelvin (K = °C + 273.15) before solving.
- How is Charles' law related to the ideal gas law?
- Charles' law is the special case of PV = nRT when n and P are constant, so V/T stays constant.
- What happens from 0 °C to 100 °C?
- On the Celsius scale this is not a doubling of absolute temperature, so volume increases by a factor of about 373/273 ≈ 1.37, not 2.
