Convert bar to psi

psi = bar × 14.5037738

Rule of thumb: multiply by 14.5, or by 15 and subtract a little. 2 bar → 29 psi.

Espresso machines are rated by pump pressure, and 9 bar — 130 psi — is the traditional brewing target. Budget machines advertising 15 or 20 bar are describing the pump's maximum, not the pressure at the coffee; most regulate down toward 9 during extraction.

• Scuba cylinders — filled to 200 bar in most of the world (2,900 psi) or 232 bar (3,365 psi); US aluminium tanks are rated at 3,000 psi (207 bar)
• Pressure washers — a 140 bar machine is sold in the US as about 2,000 psi
• Air compressors — 8 bar is 116 psi

A tyre gauge reading 2.2 bar means 2.2 bar above the surrounding air. The absolute pressure inside is about 3.2 bar, because the atmosphere adds roughly 1 bar (14.7 psi) at sea level. In imperial specs this is written psig for gauge and psia for absolute. Most everyday figures are gauge.

Tyre pressures in both units are tabled on psi to bar.

From two definitions. The bar is exactly 100,000 pascals, the pascal being the SI unit of pressure in the SI Brochure published by the International Bureau of Weights and Measures (BIPM); the psi is 6,894.757 Pa according to NIST Special Publication 811, the US guide to the SI. Dividing one by the other gives 14.5038 psi per bar.