Moles, mass, and density of an ideal gas from P, V, and T.
P V = n R T, R = 8.314 J/mol·K
How it works
The ideal gas law relates pressure, volume, temperature, and amount of an ideal gas. Given P, V, and T, the tool returns moles, molar volume, and (with a molar mass) mass and density.
Worked example
24.79 L at 100 kPa (1 bar) and 25 °C. Contains ≈ 1 mol — the molar volume of an ideal gas at SATP (25 °C, 1 bar).
Inputs
Pressure (kPa)
Volume (L)
Temperature (°C)
Molar mass (optional) (g/mol) — Leave 0 to skip mass/density.
Frequently asked questions
When does the ideal gas law break down?
At high pressure or low temperature, where molecules interact and occupy meaningful volume. Then the compressibility factor Z deviates from 1 and you need an equation of state like Peng–Robinson.
Which value of R should I use?
8.314 J/mol·K with SI units (Pa, m³, mol, K). This tool handles the unit conversions internally, so you can enter kPa, litres, and °C.
Assumptions
Ideal behavior — no compressibility (Z = 1).
For real gases at high P or low T use an equation of state (e.g. Peng–Robinson).
References
R = 8.314462618 J/mol·K (CODATA).
Related Thermodynamics tools
Vapor Pressure (Antoine) — Saturation pressure of a pure component from Antoine coefficients. Pick a preset or enter your own A, B, C.
Gas Compressor Power — Single-stage adiabatic compression power, head, and discharge temperature for an ideal gas.
Steam Tables (IAPWS-IF97) — Saturated and single-phase water/steam properties — saturation pressure/temperature, enthalpy, entropy, and specific volume — from the IAPWS-IF97 standard.