Pressure Converter
Converters · Added 15 August 2026
Convert between fifteen pressure units — the metric family from pascal to megapascal, the reference units like atmosphere and millimetre of mercury, and the imperial psi family. Factors are the exact defined values, so a conversion out and back returns the number you started with.
Result
1 bar in pound per square inch
14.5037738 psi
1 bar = 14.5037738 psi
The same value in every unit
- Pascal (Pa)
- 100,000
- Hectopascal (hPa)
- 1,000
- Kilopascal (kPa)
- 100
- Megapascal (MPa)
- 0.1
- Bar (bar)
- 1
- Millibar (mbar)
- 1,000
- Standard atmosphere (atm)
- 0.986923267
- Torr (Torr)
- 750.061683
- Millimetre of mercury (mmHg)
- 750.061576
- Inch of mercury (inHg)
- 29.5299802
- Pound per square inch (psi)
- 14.5037738
- Kilopound per square inch (ksi)
- 0.0145037738
- Pound per square foot (psf)
- 2,088.54342
- Millimetre of water (mmH₂O)
- 10,197.1621
- Kilogram-force per cm² (kgf/cm²)
- 1.01971621
Absolute and gauge pressure are not the same measurement: gauge pressure (psig, barg) is measured relative to the surrounding atmosphere, absolute pressure from a vacuum. They differ by roughly one atmosphere — about 14.7 psi — so a tyre inflated to 32 psi gauge is at about 46.7 psi absolute. This converter changes units, not the reference point.
How to use the pressure converter
- 1Enter the value you want to convert.
- 2Pick the unit you are converting from and the unit you want.
- 3The result updates as you type — there is nothing to submit.
- 4The reference table shows the same quantity in every other pressure unit at once.
- 5Use the swap button to reverse the direction.
Examples
Tyre pressure
- Input
- 32 psi
- Result
- 2.2063 bar · 220.63 kPa
Car tyres are quoted in psi in some countries and bar in others. These are the same pressure.
Standard atmosphere
- Input
- 1 atm
- Result
- 101.325 kPa · 760 mmHg · 14.6959 psi
The atmosphere is defined as exactly 101,325 pascals, which is why the kilopascal figure is exact.
Weather reporting
- Input
- 1013.25 hPa
- Result
- 1 atm · 29.92 inHg
Meteorologists use hectopascals, which are numerically identical to the older millibars.
About the pressure converter
What pressure actually is
Pressure is force spread over area — a pascal is one newton per square metre. That definition explains why the pascal is such a small unit in practical terms: a newton is roughly the weight of a small apple, and spreading it over a full square metre produces a very gentle push indeed. Everyday pressures therefore run into the thousands or hundreds of thousands of pascals, which is why kilopascals, bars and atmospheres exist.
It also explains why the same force produces wildly different pressures depending on contact area. This is the principle behind a knife edge, a drawing pin and snowshoes — force held constant, area changed deliberately in one direction or the other.
The mercury units are a historical artefact of how pressure was first measured well. A column of mercury in a sealed tube rises until its weight balances the pressure pushing on the reservoir, so the height of that column is a direct readout. Millimetres of mercury and inches of mercury are literally that height, which is why they survive in medicine and meteorology long after the instruments were replaced.
The gauge-versus-absolute trap
Almost every pressure gauge you will meet reads zero at atmospheric pressure, because it is measuring the difference between the inside of something and the air around it. That is gauge pressure, and it is the right measurement for tyres, boilers and pneumatic systems — what matters is the pressure difference across the wall.
Absolute pressure counts from a perfect vacuum instead, so atmospheric pressure reads as about 101 kPa rather than zero. Thermodynamic calculations need absolute pressure, because the gas laws are written in terms of it; using a gauge reading in the ideal gas equation produces answers that are wrong by an entire atmosphere.
The convention is usually signalled by a suffix — psig and psia, barg and bara — but the suffix is dropped constantly in practice, and a bare number is ambiguous. The rule of thumb is that anything read off a dial is gauge unless stated otherwise, and anything going into a physics calculation needs to be absolute. Converting between them is addition, not multiplication: add about 101.325 kPa to a gauge reading to get absolute at sea level, and note that the correction itself varies with altitude and weather.