Pressure Converter
Convert between pascal, kilopascal, megapascal, bar, millibar, PSI, atmosphere, mmHg, torr, inHg, kgf/cm², and more — all pressure units at once.
All Unit ConvertersAll conversions from 1 pascal
| Unit | Symbol | Value |
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How this pressure converter reconciles nineteen units built from two entirely different measuring traditions
Pressure units split roughly into two families. One family measures force spread over a defined area, which is where PSI and kgf per square centimetre come from. The other measures how high a column of liquid rises under that pressure, which is where millimetres of mercury and inches of water come from. Both are legitimate ways to describe the same physical quantity, and this tool converts freely between them by routing everything through the pascal.
All arithmetic happens client side in JavaScript. Nothing is uploaded, logged, or sent to a server.
Why the pascal is the hub
The pascal is the SI derived unit of pressure, defined by the BIPM as one newton of force per square metre of area. It is small in everyday terms, atmospheric pressure at sea level is over one hundred thousand pascals, which is exactly why kilopascals, bar, and PSI exist as more convenient everyday scales.
| Unit | Symbol | Pascals per unit |
|---|---|---|
| Pascal | Pa | 1 |
| Hectopascal | hPa | 100 |
| Kilopascal | kPa | 1,000 |
| Megapascal | MPa | 1,000,000 |
| Gigapascal | GPa | 1,000,000,000 |
| Bar | bar | 100,000 |
| Millibar | mbar | 100 |
| Microbar | µbar | 0.1 |
| PSI (pound per sq in) | psi | 6,894.757 |
| Kilopound per sq in | ksi | 6,894,757 |
| Standard atmosphere | atm | 101,325 |
| Technical atmosphere | at | 98,066.5 |
| mmHg (mercury) | mmHg | 133.322387 |
| Torr | Torr | 133.322368 |
| Inch of mercury | inHg | 3,386.389 |
| Inch of water | inH₂O | 249.0889 |
| Millimetre of water | mmH₂O | 9.80665 |
| kgf per sq cm | kgf/cm² | 98,066.5 |
| Dyne per sq cm | dyn/cm² | 0.1 |
Two atmospheres, not one
Standard atmosphere
Fixed by international agreement at exactly 101,325 pascals, representing typical air pressure at sea level. Used as the reference for defining the torr and for aviation and meteorology baselines.
Technical atmosphere
An older engineering convention equal to exactly one kilogram force per square centimetre, working out to 98,066.5 pascals. It predates the SI system and still appears in some European industrial equipment specs.
Pressure standard references
- BIPM SI Brochure defines the pascal as the SI coherent derived unit of pressure, one newton per square metre.
- NIST guide to SI pressure units covers the standard atmosphere and its exact fixed value.
- ISO 80000-4 is the international standard defining mechanical quantities including pressure and its accepted non-SI units.
Pressure readings in context
Checking tire pressure specs given in PSI against a bar reading on a European pump, converting a weather report’s hectopascal figure into inches of mercury for an American barometer, reading a blood pressure cuff’s mmHg output alongside a kilopascal figure from a medical device, and translating an industrial gauge reading between bar and technical atmosphere on imported machinery.
From the blog
Reading around units
Where measurement systems came from and why two of them still argue.
