Bar to psi
Convert bar to psi. Multiply by 14.5038, with tables for tyres, espresso machines, diving and industrial pressures.
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The formula
psi = bar × 14.5037738A bar is exactly 100,000 pascals and a psi is exactly 6894.757293168 pascals, so the ratio is that quotient — which does not terminate, hence the rounding.
To go the other way, multiply by 0.06894757293. See psi to bar.
Quick reference
| bar | psi | kPa |
|---|---|---|
| 0.5 bar | 7.25 psi | 50 kPa |
| 1 bar | 14.50 psi | 100 kPa |
| 1.5 bar | 21.76 psi | 150 kPa |
| 2 bar | 29.01 psi | 200 kPa |
| 2.2 bar | 31.91 psi | 220 kPa |
| 2.5 bar | 36.26 psi | 250 kPa |
| 3 bar | 43.51 psi | 300 kPa |
| 6 bar | 87.02 psi | 600 kPa |
| 10 bar | 145.04 psi | 1000 kPa |
1 bar is 14.5 psi, and one atmosphere is 1.013 bar — close enough that “one bar” and “one atmosphere” are used interchangeably outside precision work.
Espresso
The one place bar is the everyday unit for something that is not a tyre. Machines are advertised by their pump rating, and the brewing figure is lower than the number on the box:
| bar | psi | |
|---|---|---|
| Standard brewing pressure | 9 bar | 130.5 psi |
| Lever machine, peak | 10–12 bar | 145–174 psi |
| Advertised pump rating | 15–20 bar | 218–290 psi |
| Steam pressure | 1–1.5 bar | 14.5–21.8 psi |
A “20 bar” machine does not brew at 20 bar. That is the pump’s maximum with the outlet blocked; the actual extraction sits near 9.
Diving
| Depth | Absolute pressure | |
|---|---|---|
| Surface | 1.0 bar | 14.5 psi |
| 10 m | 2.0 bar | 29.0 psi |
| 20 m | 3.0 bar | 43.5 psi |
| 30 m | 4.0 bar | 58.0 psi |
| 40 m | 5.0 bar | 72.5 psi |
Ten metres of sea water is almost exactly one bar, which is why diving arithmetic is done in bar and why a full 200 bar cylinder is quoted as 2900 psi.
Industrial and domestic
| bar | psi | |
|---|---|---|
| Mains water | 3–5 bar | 43.5–72.5 psi |
| Domestic boiler | 1–1.5 bar | 14.5–21.8 psi |
| Compressed air, workshop | 6–8 bar | 87–116 psi |
| Scuba cylinder, full | 200–300 bar | 2900–4350 psi |
| Hydraulic system | 200–400 bar | 2900–5800 psi |
Estimating in your head
Multiply by 14.5, or multiply by 15 and take off 3%. For a rough figure, doubling and adding a zero’s worth of scale works: 2.2 bar → 2.2 × 15 = 33, minus a bit, gives 32 psi against a true 31.9.