Pressure Converter
Convert pressure between bar, psi, pascals, kilopascals, atmospheres, torr and millimetres of mercury.
How it works
Pressure is force spread over an area, and the SI unit is the pascal — one newton per square metre. A pascal is tiny, so real-world figures use kilopascals, bar or psi.
The bar was chosen to sit close to atmospheric pressure: 1 bar is 100,000 Pa, while one standard atmosphere is 101,325 Pa. They are near enough to be confused but not equal, which matters in precise work.
Millimetres of mercury and torr come from mercury-column instruments and survive in medicine and vacuum work. Blood pressure is still quoted in mmHg for that reason, long after the mercury manometer left the clinic.
The formula
bar → psi
psi = bar × 14.5038
psi → bar
bar = psi ÷ 14.5038
Any pair in this family
result = value × (factor of source ÷ factor of target)
Every unit is defined against the pa, so any combination converts in one step.
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 1 bar to psi | 1 × 14.5038 | 14.5 psi |
| Tyre at 32 psi in bar | 32 ÷ 14.5038 | 2.21 bar |
| 1 atmosphere in kPa | Standard atmosphere | 101.325 kPa |
When you'd use it
- Setting tyre pressure from a manual in the other unit
- Reading a gauge that uses bar against a spec in psi
- Converting a blood pressure or medical figure
- Engineering and physics coursework in pascals
Common questions
Is 1 bar the same as 1 atmosphere?
Very nearly, but not exactly. A bar is 100,000 Pa; a standard atmosphere is 101,325 Pa, about 1.3% higher. For tyre pressure the difference is irrelevant; for calibration or scientific work it is not.
How do I convert psi to bar for tyres?
Divide by 14.5. A 32 psi tyre is about 2.2 bar. Most European gauges read in bar and most US ones in psi, which is why the manual and the pump often disagree.
Why is blood pressure measured in mmHg?
Because the original instrument was a column of mercury, and the height of that column in millimetres was the reading. The unit outlived the instrument, and 120/80 remains far more recognisable than the equivalent in kilopascals.
Is anything I enter sent anywhere?
No. Every conversion runs in your browser, so nothing you type is uploaded, logged or stored. There is no account and no record of what you converted.