Pressure Converter
Convert PSI, bar, kPa, atm, mmHg, and more.
- psi
- bar
- kpa
- atm
- mmhg
- pressure
About Pressure Converter
Pressure shows up in different units depending on the field. Tyre gauges in the US use PSI; tyre placards in metric countries use kPa or bar. Weather reports use hPa (hectopascals) or inches of mercury. Blood-pressure cuffs use mmHg. Vacuum systems use torr or microbars. Diving gauges use bar or atmospheres. Each is just a different scaling of the same physical quantity — force per unit area — and the conversion factors are surprisingly clean (1 bar = 100 kPa = 14.5038 PSI = 0.987 atm).
This converter handles all of those at once: enter a value in one unit and see the equivalent in every other. The conversion factors are the standard internationally-agreed ones, so the values match official references.
How to use
Type a value into the input and pick the unit from the dropdown — pascals, kilopascals, hectopascals, bar, atmospheres, PSI, torr, mmHg, inches of mercury, or millibar. The conversions panel shows the value in every other unit, each with a copy button.
Tap any row to make that unit the new input — handy for chained conversions like "30 PSI to bar to kPa". Useful for car tyres (typically 32–35 PSI / 2.2–2.4 bar / 220–240 kPa), bike tyres, blood-pressure ranges, weather readings, and diving-cylinder pressures.
Frequently asked questions
How many PSI in one bar?
One bar is 14.5038 PSI. Conversely, one PSI is 0.0689 bar. A useful round figure: 1 bar ≈ 14.5 PSI ≈ 100 kPa ≈ 1 atmosphere — all four are within a few percent of each other, which is why they're often used interchangeably in everyday contexts.
What pressure should my car tyres be?
Check the placard on the driver's door jamb or the owner's manual — your specific car has a specific recommended pressure. Typical passenger-car pressures are 32–35 PSI (2.2–2.4 bar, 220–240 kPa) when cold. Bike tyres run much higher (road bikes 80–130 PSI / 5.5–9 bar); trucks higher still.
What's the unit on a weather forecast?
Hectopascals (hPa) in most countries, equivalent to the older "millibars" you may see in older textbooks — 1 hPa = 1 mbar. Average sea-level atmospheric pressure is 1013.25 hPa (or 29.92 inches of mercury in the US). A reading much below 1000 hPa means stormy weather is likely.
Why is blood pressure measured in mmHg?
For historical reasons — clinical sphygmomanometers literally pushed a column of mercury upward, and the height of that column was the pressure reading in millimetres. Modern blood-pressure cuffs use electronic sensors, but the unit (and the familiar "120 over 80" reading) survives because clinical experience and reference ranges are all in mmHg.
What does the depth of water do to pressure?
Every 10 metres of water adds roughly one atmosphere of pressure (about 1 bar, 14.5 PSI). So at 30 m underwater the ambient pressure is around 4 atm, which is why scuba divers worry about gas dissolving into their bloodstream and decompression illness on the way back up.