STP Calculator
Use the ideal gas law to relate moles, volume, and mass at standard temperature and pressure or any chosen conditions.
Convert moles of gas to volume using ideal gas law.
Moles
1
Volume (L)
22.414
How to Use This Calculator
Set temperature and pressure
Use 273.15 K and 1 atm for STP, or adjust for other conditions.
Choose conversion mode
Select whether you want moles, volume, or mass as the input quantity.
Enter known values
Provide the relevant quantity and, if using mass, the molar mass.
Read the outputs
Results list moles and volume, and include mass when applicable.
Formula
PV = nRT
Solve for the desired variable: V = nRT/P, n = PV/(RT), or combine mass and molar mass using n = mass / molar mass.
Example
One mol of gas at 273.15 K and 1 atm occupies V = 1 * 0.082057 * 273.15 / 1 = 22.414 L.
Full Description
The ideal gas law connects macroscopic properties of gases under dilute conditions. STP denotes 273.15 K and 1 atm, but the law applies to other conditions as well.
This calculator provides quick conversions for laboratory calculations, gas stoichiometry, and engineering estimates where ideal behavior is a reasonable approximation.
Frequently Asked Questions
Is STP always 273.15 K and 1 atm?
Yes for the IUPAC definition used here. Some fields use 1 bar instead of 1 atm; adjust pressure accordingly.
How accurate is the ideal gas approximation?
It works well for low-pressure gases far from condensation. Real gases need virial or cubic equations of state.
Can I enter Celsius?
Convert Celsius to Kelvin by adding 273.15 before using this calculator.
Why is molar mass required for mass conversions?
Mass does not uniquely determine moles without the molar mass, which links grams to mol amount.
Does this consider humidity or mixtures?
No. Treat each gas separately. For mixtures, use partial pressures for each component.