Ideal Gas Law Calculator
Choose which variable to solve for, enter the other three values, and calculate using the ideal gas law.
mol
Formula
PV = nRT, where P is pressure, V is volume, n is amount of substance (mol), R is the gas constant, and T is absolute temperature (K).
Example
1 mole of gas at 1 atm and 273.15 K occupies approximately 22.4 liters — the classic standard molar volume result.
Frequently Asked Questions
- Which gas constant does this use?
- 0.082057 L·atm/(mol·K) when using atm/L/K units, or 8.314462618 J/(mol·K) when using Pa/m³/K units — select the unit system that matches your inputs.
- Can I enter temperature in Celsius?
- Yes, switch the temperature unit to °C and it's converted to Kelvin (K = °C + 273.15) automatically before calculating, since the ideal gas law requires absolute temperature.
- Does this account for real (non-ideal) gas behavior?
- No, this uses the ideal gas approximation, which is accurate for many gases under normal conditions but doesn't account for intermolecular forces or molecular volume at high pressure or low temperature.
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