Ideal Gas Law Calculator (PV = nRT)
Leave one of P, V, n, T blank. The tool solves for it.
Leave exactly one of P, V, n, T blank.
Formula
PV = nRT
R = 8.31446 J/(mol·K). Temperature must be absolute (K).
R = 8.31446 J/(mol·K). Temperature must be absolute (K).
Physics behind the ideal gas law
The ideal gas law combines Boyle's law (P·V constant at fixed T), Charles's law (V/T constant at fixed P) and Avogadro's law (equal volumes at equal conditions contain equal numbers of particles). It treats gas molecules as non-interacting point particles — accurate for most gases at moderate conditions. At STP (1 atm, 273.15 K), one mole of ideal gas occupies about 22.414 L.
Worked example
n = 1 mol, T = 273.15 K, P = 1 atm
V = nRT/P = 1 · 8.31446 · 273.15 / 101325 ≈ 0.022414 m³ = 22.414 L
Related tools
FAQs
What is the ideal gas law?
PV = nRT.
What is R?
8.314 J/(mol·K), or 0.08206 L·atm/(mol·K).
When does it fail?
At very high pressure or very low temperature.