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Gas Law Calculators

Ideal gas law, Boyle's, Charles's, Gay-Lussac's and combined gas laws, gas density and molar volume.

Key gas law formulas

Ideal Gas LawPV = nRT, R = 8.314 J/(mol·K)
Boyle's LawP₁V₁ = P₂V₂ (temperature constant)
Charles's LawV₁ / T₁ = V₂ / T₂ (temperatures in kelvin)
Gay-Lussac's LawP₁ / T₁ = P₂ / T₂ (temperatures in kelvin)
Combined Gas LawP₁V₁ / T₁ = P₂V₂ / T₂
Gas Densityρ = PM / RT
Molar VolumeV_m = RT / P

Gas Law questions

Which units must I use?

Pascals, cubic metres, moles and kelvin with R = 8.314. If you prefer atm and litres, use R = 0.08206 instead.

Is molar volume 22.4 L or 24 L?

22.4 L/mol is at 0 °C and 1 atm; 22.7 L/mol at the modern STP of 100 kPa; about 24 L/mol at room temperature.