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The Ideal Gas Law relates the pressure, volume, amount, and temperature of a gas that behaves ideally: PV = nRT, where R is the universal gas constant. It's the single most general gas-behavior formula in introductory chemistry and physics.
How it works
Enter pressure in pascals, volume in cubic meters, amount in moles, and temperature in Kelvin — leave whichever one you want to solve for blank. The calculator uses R = 8.314 J/(mol·K) and applies PV = nRT to find the missing value.
- Enter pressure (Pa) — leave blank to solve for this.
- Enter volume (m³) — leave blank to solve for this.
- Enter amount of gas (mol) — leave blank to solve for this.
- Enter temperature (K) — leave blank to solve for this.
- Click Calculate to see your results.
Examples
Standard temperature and pressure
One mole of an ideal gas at standard atmospheric pressure (101,325 Pa) occupying the classic molar volume of 22.4 L (0.0224 m³) works out to a temperature very close to 273.15 K (0°C) — the textbook STP condition.
Who should use it
- Chemistry and physics coursework on gas behavior.
- Estimating an unknown gas property (pressure, volume, moles, or temperature) from the other three.
Industry applications
- Chemistry and physics education
- Basic thermodynamics and gas-behavior estimation
Advantages
- One formula covers pressure, volume, moles, and temperature together.
- A very good approximation for most gases under ordinary conditions.
Limitations
- Assumes ideal gas behavior — deviates from real gases at very high pressure or very low temperature.
Common mistakes to avoid
- Entering pressure in atm or volume in liters without converting to pascals and cubic meters first.
- Forgetting to convert Celsius to Kelvin before entering temperature.
Best practices
- Convert every input to SI units (Pa, m³, mol, K) before entering it.
- Use this law for a single-state calculation; use Boyle's/Charles's/Combined Gas Law for before-and-after comparisons of the same gas sample.
Tips
- If your numbers come out close to the classic STP figures (101,325 Pa, 0.0224 m³ per mole, 273.15 K) for one mole of gas, that's a good sign your unit conversions were done correctly.