Converts a pressure into pascals, hectopascals, kilopascals, megapascals, bar, atmospheres, millimetres of mercury and psi. One atmosphere is defined as exactly 101325 Pa, or 1013.25 hPa.
Explanation
Enter a pressure and choose its unit, and every other unit follows. Atmospheres convert to hectopascals exactly as easily as psi converts to kilopascals.
The definitions
- 1 atm = 101325 Pa = 1013.25 hPa = 760 mmHg exactly
- 1 bar = 100000 Pa, close to an atmosphere but not the same unit
- 1 psi = 6894.76 Pa
Example
Convert one atmosphere.
1 atm=101325 Pa=1013.25 hPa=760 mmHg=14.696 psi The 1013 hPa quoted in every weather forecast is exactly this.
Where each unit turns up
- Weather — hectopascals. 1013 hPa is standard; a deep low might read 990 hPa
- Blood pressure — millimetres of mercury. A reading of 120 is the pressure that lifts a column of mercury 120 mm
- Tyre pressure — kilopascals and psi. A recommended 240 kPa is 2.4 bar, or about 35 psi
- Water — every 10 m of depth adds roughly one atmosphere
Watch out
This converter treats mmHg as identical to the torr, so that one atmosphere is exactly 760 mmHg. The strict SI millimetre of mercury (133.322387415 Pa) differs by one part in ten million, a distinction neither medicine nor meteorology bothers with.