Pressure Converter

Convert between pressure units.

How it is calculated

The value is first converted to pascals using the factor of the unit you pick, then divided by the factor of each output unit: Pa = value × kfrom and result = Pa ÷ kto. The factors are 1 Pa = 1, 1 kPa = 1,000 Pa, 1 bar = 100,000 Pa, 1 psi = 6,894.757293168 Pa and 1 atm = 101,325 Pa. Results are shown for Pa, bar, psi and atm, rounded to two decimals, so very small pressures can display as 0.00. The tool treats the number as given and does not distinguish gauge pressure from absolute pressure.

Worked example

A tire is rated at 32 psi. Convert to pascals: 32 × 6,894.757293168 = 220,632.23 Pa. In bar: 220,632.23 ÷ 100,000 = 2.21 bar. In atmospheres: 220,632.23 ÷ 101,325 = 2.18 atm. So 32 psi is 220,632.23 Pa, about 2.21 bar or 2.18 atm.

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Common mistakes

  • Leaving the source unit on bar when the number is in psi or kPa. The "from" unit decides everything, so a wrong choice is off by a large factor.
  • Treating bar and atm as identical. They are close (1 atm = 1.01325 bar) but not equal, which matters for precise work.
  • Mixing gauge and absolute pressure. A tire gauge reading of 32 psi is relative to the surrounding air; the converter simply scales the number and does not add atmospheric pressure.
  • Reading a rounded two-decimal result as exact, for example converting small bar values to psi and then back again.

About this calculator

This converter moves between the units pressure is commonly reported in: pascal (Pa), the SI base unit; bar, close to standard atmospheric pressure; psi (pounds per square inch), standard in the US; and atmospheres (atm), defined as exactly 101,325 Pa. Each conversion uses these fixed physical constants rather than approximations.

It's used by scuba divers checking tank fill pressure in bar versus psi, mechanics reading tire pressure specs that differ by region, HVAC and process engineers converting between metric and imperial gauge readings, and students working through physics or chemistry problems that mix unit systems.

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