Ideal Gas Calculator
PV = nRT: solve for pressure, volume, moles or temperature.
Quick answer
- Formula: P × V = n × R × T, with R = 0.082057 L·atm/(mol·K)
- Worked example — Pressure: 4.92342 atm (full example below).
Ideal Gas Calculator
| Pressure | 4.92342 atm |
| Volume | 10.00000 L |
| Amount of gas | 2.00000 mol |
| Temperature | 300.000 K |
Two moles of gas in 10 L at 300 K exert a pressure of about 4.923 atm.
The ideal gas law combines Boyle's, Charles's and Avogadro's laws into one equation relating pressure, volume, amount and temperature for a gas that behaves ideally — a good model for most gases at ordinary pressures.
Choose the value to solve for and enter the other three; leave the solved value at 0, it is ignored. Units are fixed: pressure in atm, volume in litres, temperature in kelvin, with R = 0.082057 L·atm/(mol·K).
The formula
Worked example
Two moles of gas in 10 L at 300 K exert a pressure of about 4.923 atm.
The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.
Frequently asked questions
Why must temperature be in kelvin?
The gas laws are proportional to absolute temperature. Using Celsius would break the proportionality (and allow nonsensical zero or negative values). Add 273.15 to convert °C to K.
When does the ideal gas law fail?
At high pressures or near a gas's boiling point, molecular size and intermolecular attractions matter and real gases deviate — corrections such as the van der Waals equation are then needed.
What is R in SI units?
R = 8.314 J/(mol·K), used when pressure is in pascals and volume in cubic metres. This calculator uses R = 0.082057 L·atm/(mol·K) to match its atm and litre inputs.
Category: Science calculators
Sources & methodology
This calculator applies the formula shown on this page exactly as written, using the standard definitions for its inputs. Results are computed from the values you enter — no data is stored — and are rounded only for display.
Content last reviewed by CalcHub Editorial.
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