Pressure units
Convert vacuum and gauge readings between every unit, and see at a glance what boils at that pressure.
Pressure
In every unit
- Millibar (hPa)
- 1013.3 mbar
- Torr
- 760 Torr
- Millimetre of mercury
- 760 mmHg
- Standard atmosphere
- 1 atm
- Bar
- 1.0132 bar
- Kilopascal
- 101.33 kPa
- Pascal
- 101,325 Pa
- Megapascal
- 0.10132 MPa
- Pound per square inch
- 14.696 psi
- Inch of mercury
- 29.921 inHg
- Micron of mercury
- 760,000 µmHg
What boils at this pressure
Boiling points from Antoine constants load here.
How the numbers are defined
1 atm is exactly 101 325 Pa and 1 Torr is exactly 1/760 atm. The millimetre of mercury is defined by a mercury column at 0 °C and standard gravity, 133.322 387 Pa, so it differs from the Torr in the seventh digit. That difference never matters at the bench.
1 mbar equals 1 hPa. Vacuum gauges in Europe usually read mbar, older equipment and most literature on vacuum distillation use Torr or mmHg.
Where the boiling points come from
Each boiling point solves the Antoine equation, log10(P/mmHg) = A − B/(C + T), for the compounds in our database that have fitted constants. Values outside the temperature range a set was fitted for are marked as extrapolated. For any other compound, use the pressure–temperature nomograph.