Pounds per square inch to bar (psi to bar)

One psi is exactly 6894.757293168361 pascals (a pound-force of exactly 4.4482216152605 newtons spread over exactly 0.00064516 square meters), which is 0.0689475729 bar.

Worked through: 30 psi x 0.0689475729 = 2.06843 bar.

Going the other way, one bar is 14.50377377 pounds per square inch.

For mental arithmetic: Divide by 14.5.

The direction an American manual meets a European machine. The anchor is that 14.5 psi is 1 bar, near enough that a 30 psi tire is close to 2 bar and a 100 psi compressor is just under 7. Worth knowing that bar is not an SI unit. The SI pressure unit is the pascal, and a bar is defined as exactly 100,000 of them because a pascal is inconveniently tiny: atmospheric pressure is about 101,325 Pa, so the bar exists to make weather and hydraulics readable.

Precision is worth matching to the input. A measurement given as 10 psi carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.