Ideal-gas volume at IUPAC STP and at the older 1 atm NIST convention.
| IUPAC STP | – |
| 1 atm STP | – |
Use this calculator when a problem says “at STP” and you need to know which STP: 100 kPa versus 1 atm, both at 0 °C.
The calculation is V = n × Vm. IUPAC STP is 100 kPa and 273.15 K (22.711 L/mol). The older 1 atm convention is 22.414 L/mol. Volumes are reported in litres or gallons.
This is the ideal-gas molar volume at those two reference states. It is not a real-gas compressibility correction.
Moles: Amount of gas in moles. 1 mole is the usual textbook case.
IUPAC STP: Volume at 0 °C and 100 kPa.
1 atm STP: Volume at 0 °C and 1 atm.
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