What is Ideal Gas Law?
The Ideal Gas Law Calculator solves PV = nRT — the fundamental equation describing the behavior of ideal gases. This equation relates four properties of a gas: Pressure (P), Volume (V), amount in moles (n), and Temperature (T), connected by the universal gas constant (R).
The Ideal Gas Law combines Boyle's Law (P ∝ 1/V), Charles's Law (V ∝ T), and Avogadro's Law (V ∝ n) into one equation. It works well for most gases at moderate temperatures and pressures (not near liquefaction point).
At Standard Temperature and Pressure (STP: 0°C, 1 atm), one mole of any ideal gas occupies 22.4 liters. This is a key fact for stoichiometry involving gases.
The Ideal Gas Law is used in chemistry, physics, engineering, meteorology, and industrial processes. Applications include calculating gas volumes in reactions, determining molecular weights of gases, understanding atmospheric pressure, and designing pressurized systems.
Formula
PV = nRT
Where: P = Pressure (in atm, Pa, mmHg, or psi) V = Volume (in liters) n = Number of moles R = Gas constant = 0.08206 L·atm/(mol·K) T = Temperature (in Kelvin = °C + 273.15)
Solving for each variable: P = nRT/V V = nRT/P n = PV/RT T = PV/nR
Example — 1 mol gas at STP: P = 1 atm, n = 1 mol, T = 273.15 K V = nRT/P = 1 × 0.08206 × 273.15 / 1 = 22.4 L ✓
R in different units: 0.08206 L·atm/(mol·K) 8.314 J/(mol·K) 1.987 cal/(mol·K) 62.36 L·mmHg/(mol·K)
How to use this Ideal Gas Law Calculator?
1. Enter any 3 of the 4 variables (P, V, n, T). 2. The calculator computes PV and nRT to show if the values are consistent. 3. It also calculates what T should be for the given P, V, and n.
Note: Temperature must be in Kelvin (K = °C + 273.15). 0°C = 273.15 K, 25°C = 298.15 K, 100°C = 373.15 K.