Pressure is quoted in wildly different units depending on the field — pascals in physics, psi in plumbing and tyres, atmospheres in chemistry, and mmHg or inHg in weather and medicine. This reference converts any pressure into every supported unit at once, using exact factors.
How it works
Each unit stores an exact number of pascals per unit, with the pascal (one newton per square metre) as the SI base. Conversion is two steps:
pascals = value × pascalsPerUnit[from]
result = pascals ÷ pascalsPerUnit[to]The anchor points are the standard atmosphere 1 atm = 101325 Pa, the 1 bar = 100000 Pa (exact), and 1 psi = 6894.757293 Pa. The torr is defined as exactly 1/760 atm, and the conventional millimetre of mercury (133.322387415 Pa) is almost — but not exactly — equal to it.
Tips and example
- To convert 32 psi (a typical tyre pressure) to bar:
32 × 6894.757 ÷ 100000 ≈ 2.21 bar. - One atmosphere ties the systems together:
1 atm = 1.01325 bar = 14.696 psi = 760 torr = 29.92 inHg. - For weather, US reports use inHg while most of the world uses hPa (millibars);
1013.25 hPa = 1 atm.
Results that are very large or very small are shown in scientific notation so they remain readable.