Solve the ideal gas law, PV = nRT, for whichever variable you're missing — pressure, volume, moles, or temperature.
The ideal gas law, PV = nRT, relates a gas's pressure (P), volume (V), amount in moles (n), and absolute temperature (T), tied together by the universal gas constant R = 8.314 J/(mol·K) — a foundational relationship in chemistry and physics for describing how gases behave under different conditions.
Pick which one of the four variables you want to solve for, fill in the other three, and the calculator rearranges the equation accordingly — the same algebra you'd do by hand, just automated so you don't need to manually isolate the variable each time.
This works best for gases at everyday, moderate pressures and temperatures, where the ideal-gas approximation genuinely holds well. Real gases start to deviate meaningfully from this idealized behavior at very high pressure or very low temperature, where intermolecular forces and molecular volume (which the ideal gas law ignores) start to matter.
PV = nRT relates a gas's pressure (P), volume (V), amount in moles (n), and absolute temperature (T), with R as the universal gas constant (8.314 J/(mol·K)). It's an approximation that works well for most gases at everyday pressures and temperatures.
The law only works with absolute temperature, where zero really means zero molecular motion. Celsius and Fahrenheit have arbitrary zero points, so this calculator converts them to Kelvin internally before solving.
At very high pressures or very low temperatures, real gas molecules take up meaningful volume and attract each other — effects the ideal gas law ignores. For precise work in those conditions, a real-gas equation of state (like Van der Waals) is more accurate.
