Pressure Converter

Convert between Pascal, bar, atm, psi, mmHg, kPa, millibar and inHg — instantly.

How to use

  1. Type a value and choose the unit you are converting from.
  2. All other units update at once in the table below.
  3. The conversion factors are exact physical constants — no approximation.

About this tool

Pressure has too many units because too many fields invented their own. Meteorology uses millibars and inches of mercury, medicine uses millimetres of mercury, engineering uses Pascal and bar, American industry uses PSI, and chemistry uses atmospheres. They all describe the same physical quantity — force per unit area — and the conversion factors are exact, but the fact that there are eight common units means looking them up is a regular chore.

This converter takes a value in any of the eight units and shows the equivalent in all the others. The conversion goes through Pascal, the SI unit, using the exact factors defined by the international standards. One atmosphere is exactly 101,325 Pa, one bar is exactly 100,000 Pa, and one PSI is exactly 6,894.757 Pa. The rest follow.

The calculation runs in your browser. Type a tire pressure in PSI and read it in bar, or type a blood pressure in mmHg and read it in kPa, or type a weather station reading in mbar and read it in inHg. Nothing is uploaded or stored.

The formula

1 atm = 101,325 Pa = 1.01325 bar = 14.696 psi = 760 mmHg = 1013.25 mbar = 29.921 inHg.

Frequently asked questions

What is the SI unit of pressure?

The Pascal (Pa), defined as one newton per square metre. It is a small unit — atmospheric pressure is about 101,325 Pa — so kilopascal (kPa) is more common in practice.

What unit do tire gauges use?

PSI in the US, bar in Europe and Brazil. A typical car tire is around 32 psi or 2.2 bar.

What is mmHg used for?

Blood pressure measurements. A reading of 120/80 mmHg is about 16/10.7 kPa.

Are the conversion factors exact?

The ones between atm, bar, Pa and mbar are exact by definition. PSI and mmHg involve physical constants (the inch and the density of mercury) and are exact to the precision shown.

Does it handle negative pressure (vacuum)?

Yes. Negative values are valid and convert normally. A negative gauge pressure means vacuum below atmospheric.

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