Pressure converters
Convert pressure between psi and bar — tyre pressures, compressors, pumps and gauges.
About pressure conversion
Pressure is force per area. The SI unit is the pascal, but it is tiny, so practical units are the bar (100 000 Pa, close to atmospheric pressure), the psi (pound-force per square inch, the US unit for tyres, compressors and pipes), the kilopascal used on Japanese and Australian tyre placards, and the atmosphere and millimeters of mercury used in science and medicine.
Conversion factors at a glance
| Unit | Equals |
|---|---|
| 1 bar | 14.504 psi = 100 kPa = 0.987 atm = 750 mmHg |
| 1 psi | 0.0689 bar = 6.895 kPa |
| 1 atm | 1.013 bar = 14.70 psi = 101.3 kPa |
| 1 kPa | 0.01 bar = 0.145 psi |
Which converter do I need?
Tyres. Psi to bar when the car's placard is American and the pump at the petrol station is European, and the reverse when it is the other way round. A typical car tyre runs at 2.2–2.5 bar, 32–36 psi. Workshops and pressure washers. Compressors are rated in psi in the US and bar elsewhere. Diving. Cylinders hold 200–232 bar, about 3 000 psi; every 10 m of depth adds one bar. Coffee. Espresso is extracted at about 9 bar, 130 psi.
Gauge and absolute
Most gauges read pressure above atmospheric; scientific values often include the atmosphere. The conversion factor is the same either way, but do not compare a gauge reading with an absolute one without adding or subtracting the roughly 1 bar of the air around us.
Common questions
How many psi is 1 bar? 14.5 psi. What is normal tyre pressure? 2.2–2.5 bar, 32–36 psi, for most cars; check the placard in the door jamb. What is atmospheric pressure? 1.013 bar, 14.7 psi, 101.3 kPa. How many bar is 100 psi? 6.9 bar. What pressure does an espresso machine use? About 9 bar, 130 psi.