Pressure Converter

Tyre gauges read psi or bar, weather maps use hectopascals, blood pressure uses millimetres of mercury and engineers quote megapascals. The pascal is one newton per square metre; every other pressure unit here is an exact multiple of it.

How to use the Pressure Converter

1. Pick the unit you are starting from in the From menu and type your value.
2. Pick the unit you want in the To menu. The heading changes to match, for example “Bar to Psi Converter”.
3. The most common pressure units are shown below at the same time, so you can compare them at a glance.
4. Type into any result to convert backwards, then use Copy results. The copied text starts with the heading for your chosen units.

Results update as you type. Everything is calculated in your browser.

How it works

Each of the 18 pressure units on this page is defined by an exact factor relative to the pascal, the base unit: 1 bar = 100,000 Pa and 1 psi = 6,894.7573 Pa, for example. The calculator first turns the value you type into pascals, then turns that into the unit you picked in the “To” menu and into standard atmospheres, pascals and kilopascals. Typing into any result works backwards the same way, so the bar and psi values always describe the same amount.

How to convert pressure units

1. Choose the unit you have in the From menu and type the value, for example 1 bar.
2. Choose the unit you want in the To menu, for example psi. The page heading changes to “Bar to Psi Converter”.
3. The calculator multiplies by the pascal factor of the “from” unit and divides by the factor of the “to” unit: 1 bar × 100,000 ÷ 6,894.7573 = 14.503774 psi.

1 bar in common units

Bar conversion table

Pressure units explained

Bar (bar)

One bar is exactly 100,000 Pa, close to average atmospheric pressure. European tyre pressures, diving, espresso machines and industrial gauges use bar.

Pound per square inch (psi)

Pounds per square inch is the pressure of one pound-force on one square inch, about 6,895 Pa. U.S. tyre gauges, compressors and hydraulic equipment read psi.

Standard atmosphere (atm)

The standard atmosphere is exactly 101,325 Pa, the average air pressure at sea level. Chemistry problems and diving depth calculations often use atm.

Pascal (Pa)

The pascal is the SI unit of pressure: one newton per square metre. It is small, so kilopascals and megapascals are used in practice.

Kilopascal (kPa)

A kilopascal is 1,000 Pa. Tyre pressures in Canada and Australia, weather data and boiler gauges often use kPa; standard air pressure is 101.325 kPa.

Megapascal (MPa)

A megapascal is one million pascals, the same as one newton per square millimetre. Material strengths and hydraulic pressures are given in MPa.

Millimetre of mercury (mmHg)

Millimetres of mercury measure pressure by the height of a mercury column. Blood pressure is reported in mmHg, and 760 mmHg is one standard atmosphere.

Inch of mercury (inHg)

Inches of mercury are used for barometric pressure in U.S. weather reports and aviation altimeter settings; standard pressure is 29.92 inHg.

Torr (Torr)

The torr is exactly 1/760 of a standard atmosphere, named after Evangelista Torricelli, inventor of the barometer. Vacuum systems are rated in torr.

Inch of water (inH₂O)

Inches of water column measure small pressures such as gas-line pressure, duct static pressure and chimney draft.