Solve PV = nRT for any variable: pressure, volume, temperature, or moles of an ideal gas.
| Variable | Unit | Description |
|---|---|---|
| P | atm | Pressure |
| V | L | Volume |
| n | mol | Amount of substance |
| R | 0.08206 L·atm/(mol·K) | Gas constant |
| T | K | Absolute temperature |
At high pressures (>10 atm) or low temperatures (near condensation). Real gases deviate due to intermolecular forces and molecular volume. Use the Van der Waals equation for accuracy.
Add 273.15. For example, 25 degrees C = 298.15 K. Never use Celsius in gas law calculations.
Try this related calculator.
Open →Try this related calculator.
Open →Try this related calculator.
Open →Enter any three of: pressure (P), volume (V), moles (n), or temperature (T). The calculator solves for the fourth using the ideal gas law.
PV = nRT, where R = 8.314 J/(mol·K) = 0.0821 L·atm/(mol·K). At STP (0°C, 1 atm): 1 mole of gas = 22.4 liters.
2 moles of gas at 300 K and 1 atm: V = nRT/P = 2 × 0.0821 × 300 / 1 = 49.26 liters.
The ideal gas law works best at high temperatures and low pressures. Real gases deviate at high pressure and low temperature. Always convert temperature to Kelvin (K = °C + 273.15). Match your units to the R constant you use.