The gas law calculator solves the ideal gas law PV = nRT for any variable — pressure, volume, moles, or temperature. Supports kPa, atm, and bar for pressure; °C, K, and °F for temperature. Perfect for chemistry and physics coursework.
Ideal Gas Law Calculator (PV = nRT)
How to Use the Gas Law Calculator
The ideal gas law PV = nRT connects pressure, volume, moles, and temperature. Select any one variable to solve for, then enter the other three.
Units Handled Automatically
Pressure: kPa, atm (1 atm = 101.325 kPa), bar (1 bar = 100 kPa), Pa. Temperature: °C (add 273.15 for Kelvin), K, °F ((°F−32) × 5/9 + 273.15). Volume: always in liters. The gas constant R = 8.314 L·kPa/(mol·K).
Standard Conditions
STP (standard temperature and pressure): 0°C (273.15 K), 1 atm (101.325 kPa). At STP, 1 mol ideal gas = 22.414 L. SATP: 25°C (298.15 K), 100 kPa. At SATP, 1 mol = 24.789 L.
Example
How many moles of gas at 2 atm, 10 L, 300 K? n = PV/(RT) = (202.65 kPa × 10 L) / (8.314 × 300) = 2026.5 / 2494.2 = 0.813 mol.
FAQ
What is the ideal gas law?
The ideal gas law PV = nRT relates pressure (P), volume (V), moles of gas (n), the universal gas constant (R = 8.314 J/mol·K), and temperature (T in Kelvin). At standard conditions (0°C, 1 atm), 1 mole of ideal gas occupies 22.414 liters.
What is the difference between ideal and real gases?
Ideal gases assume no intermolecular forces and that gas molecules have no volume. Real gases deviate from ideal behavior at high pressures and low temperatures. The van der Waals equation corrects for these deviations. For most everyday calculations at moderate temperatures, the ideal gas law is accurate within a few percent.
Is this calculator free?
Yes, completely free with no signup required. All calculations run in your browser.
Is my data private?
Yes. All calculations run locally. Nothing is transmitted.
What are the units for the gas constant R?
R = 8.314 J/(mol·K) in SI units. When using atm and liters: R = 0.08206 L·atm/(mol·K). When using kPa and liters: R = 8.314 L·kPa/(mol·K). This calculator handles unit conversion automatically based on your selected pressure unit.