Bar to PSI
Convert bar (bar) to psi (psi). Both measure force per area, and the conversion comes up in weather, automotive, diving work.
The Formula
``
psi = bar × 14.503773773
bar = psi × 0.0689475729317
`
One bar is 14.5038 psi, and one psi is 0.068948 bar.
Conversion Table
| Bar | PSI |
|---|---|
| 1 bar | 14.5038 psi |
| 2 bar | 29.0075 psi |
| 5 bar | 72.5189 psi |
| 10 bar | 145.0377 psi |
| 25 bar | 362.5943 psi |
| 50 bar | 725.1887 psi |
| 100 bar | 1,450.38 psi |
| 500 bar | 7,251.89 psi |
| 1,000 bar | 14,503.77 psi |
The Other Direction
| PSI | Bar |
|---|---|
| 1 psi | 0.068948 bar |
| 2 psi | 0.137895 bar |
| 5 psi | 0.344738 bar |
| 10 psi | 0.689476 bar |
| 25 psi | 1.7237 bar |
| 50 psi | 3.4474 bar |
| 100 psi | 6.8948 bar |
| 500 psi | 34.4738 bar |
| 1,000 psi | 68.9476 bar |
What Each Unit Is
Bar (bar) — exactly 100,000 pascals — close to, but not exactly, one atmosphere. Introduced by meteorologist Vilhelm Bjerknes; weather maps use millibars.
PSI (psi) — pounds-force per square inch, equal to 6,894.76 pascals. The imperial pressure unit, still standard for US tyres, plumbing and compressed air.
A Sense of Scale
Sea-level pressure is about 1.013 bar- Diving adds 1 bar per 10 m of depth
- Car tyres run at 32–35 psi
- Household water is 40–60 psi
Doing It in Your Head
Multiply by 29, then divide by 2. That is off by 0.03% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 145.0377 psi 145 psi 1,450.38 psi 1,450 psi
Precision
The factor 14.503773773 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
In Code
`javascript
const barToPsi = (value) => value * 14.503773773;
``
Where This Conversion Comes Up
- Weather
- Automotive
- Diving
- Aviation
- HVAC
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 bar with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 bar becomes | Error |
|---|---|---|---|
| 0 | 15 | 2,055 | 3.4214% |
| 1 | 14.5 | 1,986.5 | 0.0260% |
| 2 | 14.5 | 1,986.5 | 0.0260% |
| 3 | 14.504 | 1,987.05 | 0.0016% |
| 4 | 14.5038 | 1,987.02 | 0.0002% |
The right number of significant figures is set by your input, not by the converter. If you measured bar to three significant figures, the answer in psi is only good to three — writing more digits claims precision the measurement never had.