Ideal Gas Law Calculator
Ideal gas law calculator (PV = nRT): solve for pressure, volume, moles or temperature in any units, with R = 8.314 J/(mol·K).
P · V = n · R · T
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
The ideal gas law PV = nRT relates pressure, volume, amount and absolute temperature of a gas. R is the molar gas constant, 8.314462618 J·mol⁻¹·K⁻¹.
It works well for most gases at ordinary pressures and temperatures. At high pressure or near condensation, use the van der Waals equation instead. Temperatures in °C or °F are converted to kelvin automatically.
Formula
P · V = n · R · T
| Symbol | Quantity | Units |
|---|---|---|
| P | Pressure | Pa, kPa, MPa, hPa, bar, mbar, atm, Torr, mmHg, psi, inHg |
| n | Amount of gas | mol, mmol, µmol, nmol, kmol |
| T | Temperature | K, °C, °F, °R |
| V | Volume | L, mL, µL, m³, dm³, cm³, gal, gal (UK), qt, pt, cup, fl oz, ft³, in³ |
Constants used: R = 8.314462618 J·mol⁻¹·K⁻¹
Worked example
Given: P = 1 atm · n = 1 mol · T = 0 °C
V = n · R · TP
Result: V = 22.414 L
Frequently asked questions
What is the molar volume of an ideal gas?
At 0 °C and 1 atm (STP), one mole occupies 22.414 L. At 0 °C and 1 bar (IUPAC STP) it is 22.711 L.
Why must temperature be in kelvin?
The law is proportional to absolute temperature. The calculator converts °C and °F for you, so you can type them directly.