Pressure converter — bar, Pa, hPa, kPa, psi, atm, mmHg

Pressure is force per unit area (F/A). The SI base unit is the pascal (Pa = N/m²). Common units include bar (1 bar = 100,000 Pa), hPa (meteorology), kPa, psi (pounds per square inch — used in the US and UK), atm (standard atmosphere) and mmHg (millimetres of mercury — medicine).

1 bar = 100,000 Pa = 1,000 hPa = 100 kPa. A bar is very close to atmospheric pressure (1 atm ≈ 1.01325 bar). It is widely used in engineering, hydraulics and for tyre pressure.

PSI (pound per square inch) is a pressure unit mainly used in the USA and UK. 1 psi ≈ 6,894.76 Pa ≈ 0.0689 bar. It is used for tyre pressure (e.g. 32 psi ≈ 2.2 bar), hydraulic and pneumatic systems.

The physical atmosphere (atm) is defined as mean atmospheric pressure at sea level: 1 atm = 101,325 Pa = 1,013.25 hPa ≈ 1.01325 bar ≈ 14.696 psi ≈ 760 mmHg. Used in chemistry (STP conditions), diving and astronautics.

The hectopascal (hPa) is convenient in meteorology because atmospheric pressure at sea level is about 1013 hPa — an easy number to remember. It is numerically identical to the millibar (1 hPa = 1 mbar).

Millimetre of mercury (mmHg) derives from mercury manometers. 1 mmHg ≈ 133.32 Pa. Commonly used in medicine for blood pressure (e.g. 120/80 mmHg) and intraocular pressure, as well as in vacuum technology.

Multiply the bar value by 14.5038. Example: 2 bar × 14.5038 ≈ 29 psi. Reverse: 1 psi ≈ 0.0689 bar. Quick rule: 1 bar ≈ 14.5 psi. The converter does this with full accuracy.

Typical car tyre pressure is 1.8–2.5 bar (about 26–36 psi). Check the recommended value in your owner's manual or the label inside the driver's door jamb. Too low increases fuel consumption and puncture risk; too high reduces grip and comfort.

Absolute pressure is measured from absolute vacuum (0 Pa). Gauge pressure is measured relative to atmospheric pressure — e.g. a tyre gauge reads 2 bar gauge, but absolute pressure inside is about 3.013 bar. This converter works with absolute pressure values.

During diving, pressure increases by about 1 atm (1.01325 bar) for every 10 metres of depth. At 10 m the pressure is about 2 atm (202.65 kPa); at 30 m about 4 atm. This is critical for calculating breathing mixtures, decompression limits and decompression sickness risk.