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Ideal Gas Law Calculator

Ideal Gas Law Calculator

Enter any three of P, V, n, T. Leave the unknown blank — we’ll solve it instantly.

Decimals:
3
Additional parameters
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How the Ideal Gas Law calculator works

Provide any three variables and leave the fourth blank. The app converts all inputs to SI units — pressure in pascals (Pa), volume in cubic meters (m³), temperature in kelvins (K), amount in moles (mol) — then applies PV = nRT with R = 8.314462618 J·mol⁻¹·K⁻¹. The result is converted back to your chosen unit and rounded to your selected decimal places.

What is an ideal gas?

An ideal gas is a model where particles are point-like with no intermolecular forces. Many real gases behave approximately ideally at moderate temperatures and low pressures.

Ideal gas law equation

PV = nRT. Rearrangements: P = nRT/V, V = nRT/P, n = PV/(RT), T = PV/(nR). Always use absolute temperature (kelvins).

Ideal gas constant

This tool uses the SI value R = 8.314462618 Pa·m³·mol⁻¹·K⁻¹. Unit conversion lets you work with kPa, atm, bar, psi, L, mL, and more.

FAQs

When can I use the ideal gas law?
When gases are near ideal conditions: low to moderate pressures and not near condensation. For high accuracy at extremes, use real-gas models (e.g., van der Waals, Redlich–Kwong).
What is the pressure of 0.1 moles of a gas at 50 °C in a cubic meter?
P = nRT/V = 0.1×8.314462618×(50+273.15)/1 ≈ 268.68 Pa (≈0.269 kPa, 0.00265 atm). Set n=0.1 mol, V=1 m³, T=50 °C and leave P blank.
What gas laws can be identified within PV = nRT?
Boyle’s law (P∝1/V at constant n,T), Charles’s law (V∝T at constant n,P), Gay-Lussac’s law (P∝T at constant n,V), and Avogadro’s law (V∝n at constant P,T).
How do I calculate temperature given moles, volume and pressure?
Use T = PV/(nR). Convert to SI first, compute T in kelvins, then convert to °C or °F using the unit switcher.