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Ideal gas law

pressure: volume:
Pa cm3
bar l
atm m3
number: temperature:
mol K
molecules °C
molar mass: mass:
g / mol g
kg / mol kg


The results have been rounded to significant digits.

This is a calculator covering the ideal gas law P·V = n·R·T. When three of the four quantities pressure P, volume V, molar number n, and temperature T are known, the fourth quantity is calculated for an ideal gas. When the molar mass of the gas is known, the mass of the gas can be used instead of the molar number.

Usage: Type the values of three quantities into the corresponding fields of either pressure, volume, number or temperature with the correct unit. The calculation is performed after a further click with the mouse on any free space of the window or on the "calculate" button. All results and the input values are shown in several units. Move the mouse over a unit or click on it to read its full name.
The calculation is performed using the values in those three input fields changed last. After the calculation, these fields are coloured lightgreen while the fields displaying calculated values are coloured pink. For another calculation with other values just type these into the corresponding fields. In the case that you want to do another calculation with completely different input, type the "reset" button.
After the molar mass of the gas has been typed in (the input field is coloured light grey), the mass will be calculated after a change of the mole number (also after a calculation). Vice versa the molar number will be calculated after a change of the mass.

Example: What is the number of molecules (in moleculec/cm3) of air under normal conditions. Type the following values: 1 cm3 for the volume, 1 atm or 1013.25 Pa for the pressure, and 0 °C for the temperature. After a click with the mouse on any free space of the window or on the "calculate" button you can read the result (2.6868·1019 molecules / cm3).
Now you want to calculate what is the mass of one cubic meter of air under the sane cinditions. An averaged molar mass of air of 28.9644 g/mol is assumed. Type this value into the corresponding field. The input fields for the molar mass show a light grey color after a further mouse click. Next change the input of the volume to 1 m3. After a click with the mouse on any free space of the window or on the "calculate" button you can read the result again (1.2922 kg / m3).

- Large and small numbers are written exponentially. As example 2.3e5 = 2.3⋅105 = 230000 or 4.5e-5 = 4.5⋅10-5 = 0.000045.
- There is no warranty for the conversion. Cactus2000 is not responsible for damage of any kind caused by wrong results.
- Please send an email if you have suggestions or if you would like to see more conversions to be included.

© Bernd Krüger, 10.11.2007

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Bernd Krüger, 2020