How to Use the Ideal Gas Law (PV = nRT)

The ideal gas law combines Boyle's, Charles's, and Avogadro's laws into one equation: PV = nRT. It approximates real gas behavior at low pressure and high temperature.

Step-by-step

1. Identify the four variables: P, V, n, T — one will be unknown.
2. Convert temperature to kelvin: K = °C + 273.15.
3. Choose R to match your pressure and volume units (0.08206 L·atm/mol·K is common).
4. Rearrange: solve for the unknown (e.g., P = nRT/V).
5. Check units cancel correctly.
6. Use our Ideal Gas Law Calculator for any variable.

Open the Ideal Gas Law Calculator to apply these steps with your own numbers instantly.

Frequently asked questions