Ideal Gas Law Calculator
Solve pressure, volume, temperature or moles from the ideal gas law PV = nRT — the equation behind every gas calculation.
Result
—
In Celsius (if T) —
✉ Email me this result
</> Embed this calculator
Paste this into any website or blog post. It is free — the small "powered by" link must stay visible.
How it works
PV = nRT, R = 8.314 J/(mol·K) with SI units, or 0.0821 L·atm/(mol·K)Frequently Asked Questions
How do I use the ideal gas law?
PV = nRT relates pressure, volume, moles and temperature. Solve for any one variable given the other three: 1 mole of gas at 1 atm and 273 K (0°C) occupies about 22.4 L — the classic molar volume at STP.
What units does R use?
0.0821 L·atm/(mol·K) is convenient for atmospheres and liters; 8.314 J/(mol·K) is the SI value for pascals and cubic meters. This calculator uses the atm/L version — convert your units to match, or ask if you need the SI version.
Does the ideal gas law work for all gases?
It's an excellent approximation at typical temperatures and pressures for many gases, but breaks down at very high pressure or very low temperature, where real gas behavior (accounted for by equations like van der Waals) diverges.