Pick what you want to solve for — Pressure, Volume, Temperature, or Moles — then fill in the remaining known values with your preferred units, and this Ideal Gas Law Calculator returns the calculated value alongside the formula used and the Gas Constant (R) for full transparency.
Calculated Value
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Unit
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Formula Used
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Gas Constant (R)
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The ideal gas law equation is PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant (8.314 J/mol·K), and T is temperature in Kelvin.
An ideal gas is a theoretical gas composed of randomly moving point particles that don't interact except through elastic collisions. Real gases approximate ideal behavior at high temperatures and low pressures.
The ideal gas law works best for gases at high temperatures and low pressures. It's less accurate for gases near their condensation point or at very high pressures where intermolecular forces become significant.
The universal gas constant R = 8.314 J/(mol·K) or 0.08206 L·atm/(mol·K). The value depends on the units used for pressure, volume, and temperature in your calculation.
To find temperature, rearrange PV = nRT to T = PV/(nR). Convert pressure to Pa, volume to m³, and the result will be in Kelvin. Then convert to your desired temperature unit if needed.
Using PV = nRT: P = nRT/V = (0.1 mol)(8.314 J/mol·K)(323.15 K)/(1 m³) = 268.6 Pa or about 0.00265 atm.
Pressure: atm, Pa, kPa, bar, torr, mmHg. Volume: L, mL, m³, cm³, dm³. Temperature: K, °C, °F, °R. Moles are always in mol. The calculator automatically converts between units.
The ideal gas law equation has four variables (P, V, n, T). To solve for one unknown variable, you must provide the other three known values. This calculator solves for whichever variable you select.