Bar to Psi conversion

Bar to psi

Bar is the metric pressure unit you meet on European tyre pumps, espresso machines, pressure washers, diving computers and hydraulic gauges. Psi is its American counterpart. 1 bar = 14.5038 psi, so multiply bar by 14.5038. The bar is defined as exactly 100 000 pascals; the psi is the force of one pound on one square inch, 6 894.76 pascals.

Quick estimate

Multiply by 15 and take off 3 %, or just multiply by 14.5. A 2.5 bar tyre is 36 psi; a 9 bar espresso machine is 130 psi.

• 0.5 bar = 7.25 psi
• 1 bar = 14.5 psi
• 1.5 bar = 21.76 psi
• 2 bar = 29.01 psi
• 2.2 bar = 31.91 psi (a typical car tyre)
• 2.5 bar = 36.26 psi
• 3 bar = 43.51 psi
• 5 bar = 72.52 psi
• 9 bar = 130.53 psi (espresso extraction)
• 10 bar = 145.04 psi
• 200 bar = 2 900.75 psi (a scuba cylinder)

Everyday pressures

Tyres. European placards give bar (sometimes kPa); American gauges read psi. Coffee. Espresso machines are rated at 9–15 bar; 15 bar is 218 psi. Water. Mains water pressure in homes is 2–5 bar (29–73 psi); a pressure washer runs at 100–200 bar (1 450–2 900 psi). Diving. A full cylinder holds 200–232 bar, 2 900–3 365 psi; recreational dive depth adds one bar of pressure for every 10 m of water.

Bar, atmosphere and kPa

One bar is 0.987 standard atmospheres, close enough that the two are often used interchangeably. In kilopascals, 1 bar = 100 kPa, so a 220 kPa tyre placard means 2.2 bar or 32 psi.