Ideal Gas Calculator
Solve pressure, volume, amount of gas or absolute temperature using PV=nRT. Select explicit units and inspect the substituted equation and equivalent quantities.
YOUR CALCULATION
Result
—
Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Convert pressure to pascals, volume to cubic meters, amount to moles and temperature to kelvin. Rearrange PV=nRT for the unknown. R is 8.31446261815324 J/(mol·K).
PV=nRT; P=nRT/V; V=nRT/P; n=PV/(RT); T=PV/(nR)
Worked example
At absolute pressure 101.325 kPa, temperature 25 °C (298.15 K) and amount 1 mol, an ideal gas occupies about 24.4654037 L.
Assumptions and input details
Pressure must be absolute, not gauge pressure. All known quantities must be positive; gas temperature must be strictly above 0 K. The unknown numeric field is ignored, while its unit selector determines the output. This is an ideal-gas approximation; no real-gas, condensation, mixture-composition or high-pressure correction is made. A standard atmosphere is exactly 101325 Pa. R uses the defined Boltzmann and Avogadro constants; displayed results remain floating-point approximations.
References: OpenStax: ideal gas model · NIST: molar gas constant
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
The 36 volume definitions distinguish US liquid, US dry and Imperial measures. Cups carry an explicit definition. Japanese shō is 2401/1331 L and a gō is one tenth of it; the explicitly labelled 180 mL rice cup is separate.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
NIST measurement tables · UK Imperial definitions · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Enter a chemical formula and mass or amount of substance. Find molar mass, moles and particle count with an element-by-element breakdown.
Convert pressure across SI and other common units. Distinguish absolute and gauge readings using a reference pressure you enter, and compare both in a unit table.
Convert Celsius, Fahrenheit, kelvin and Rankine. Distinguish actual temperatures from temperature changes, and compare all four scales in a table.
Reserved advertising space.