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.

Worked examples

A 2.4 bar tyre placard. 2.4 × 14.504 = 34.8 psi — set an American gauge to 35.

A 150-bar pressure washer. 150 × 14.504 = 2 176 psi, mid-range in US catalogues.

Mains water at 3 bar. 43.5 psi, normal domestic pressure in both systems.

Frequently asked questions

How many psi is 1 bar? 14.504 psi.

What is 2 bar in psi? 29 psi.

Are bar and atm the same? Almost: 1 atm is 1.01325 bar. For tyres and pumps the difference does not matter; in a lab it does.

Related conversions

Psi to bar reverses this page. One bar is also 100 kPa and 750 mmHg.

Good to know

Tyre pressure changes with temperature: roughly 0.1 bar (1.5 psi) for every 10 °C. A tyre set to 2.4 bar in a warm garage reads 2.2 bar on a frosty morning, and a tyre checked after a long drive reads high. Manufacturers' figures are for cold tyres, so check them before driving, not after. The same applies to bicycle tyres pumped indoors and ridden in winter, and to pressure gauges on compressors that warm up in use. Digital gauges are typically accurate to about 0.05 bar or 1 psi, which is fine for tyres but not for calibrating instruments. If two gauges disagree by more than 0.2 bar, trust neither until one has been checked against a known reference.