Ideal Gas Law Calculator
Enter any three of moles, temperature, volume and pressure to compute the fourth via PV = nRT.
Input Data
Results
At a glance:The ideal gas law PV = nRT combines Boyle's, Charles's and Avogadro's laws into one equation relating pressure P, volume V, amount n (moles) and absolute temperature T: P·V = n·R·T, with R = 8.314 J/(mol·K). It assumes point particles with no interactions and negligible volume, valid for low-density gases. In other units P(atm)·V(L) = n·0.08206·T. Solve for any variable: P = nRT/V, V = nRT/P, n = PV/(RT), T = PV/(nR). Deviations at high pressure/low temperature are described by the compressibility factor Z (real-gas equations like van der Waals). This tool solves for the missing of the four and reports pressure in Pa and atm.
Formula
PV = nRT
P = nRT/V, V = nRT/P, n = PV/(RT), T = PV/(nR)
R = 8.314 J/(mol·K)
$$PV = nRT$$$$P = \dfrac{nRT}{V}$$How to Use
- Enter any three of n, T, V, P.
- The calculator returns the fourth and pressure in atm.
Case Studies
Balloon volume
n = 1 mol, T = 300 K, P = 101325 Pa.
V = 1×8.314×300/101325 ≈ 0.0246 m³ (24.6 L).
Matches the molar volume at STP (~22.7 L at 273 K).
FAQ
When is the ideal gas law accurate?
At low pressure and high temperature (low density) where intermolecular forces and molecular volume are negligible. Real gases deviate near liquefaction.
Why must temperature be in Kelvin?
The law uses absolute temperature; 0 K is the true zero of molecular motion. Using °C would give wrong (even negative) results. T(K) = T(°C)+273.15.
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References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.