Pressure Converter
Convert pressure between pascals, kilopascals, bar, PSI, atmospheres, mmHg and torr — for tyres, weather, diving and engineering.
How pressure conversion works
Pressure is force per unit area, and the SI unit is the pascal (one newton per square metre). All the units
here are defined in pascals, so conversions are exact:
- 1 bar = 100,000 Pa exactly · 1 kPa = 1,000 Pa
- 1 psi (pound-force per square inch) = 6,894.757 Pa · 1 bar = 14.5038 psi
- 1 atm = 101,325 Pa exactly (standard sea-level air pressure)
- 1 mmHg (Torr) = 133.322 Pa — the pressure of a 1 mm mercury column
Different fields kept different units: tyres are quoted in bar or psi, weather maps in hPa (1 hPa = 100 Pa,
identical to the old millibar), medicine in mmHg, and engineering in kPa or MPa.
Handy approximations
- bar → psi: multiply by 14.5 (2.5 bar ≈ 36 psi)
- psi → bar: divide by 14.5 (32 psi ≈ 2.2 bar)
- bar ≈ atm for everyday accuracy (they differ by 1.3%)
- kPa → psi: divide by 7 for a rough figure (220 kPa ≈ 32 psi)
Worked example
A tyre inflated to 2.5 bar: 2.5 × 100,000 ÷ 6,894.757 = 36.26 psi. The same
pressure is 250 kPa, 2.467 atm, or 1,875 mmHg.
Frequently asked questions
Is 2 bar the same as 29 psi?
Very nearly: 2 bar = 29.01 psi (1 bar = 14.5038 psi). For tyre pressure the difference is negligible — a gauge reading 29 psi is effectively 2.0 bar.
What tyre pressure is 2.5 bar in psi?
2.5 bar = 36.26 psi = 250 kPa. Typical car tyre pressures fall between 2.0 and 2.8 bar (29–41 psi); check the sticker in your door jamb for the exact figure.
How many psi is 1 atmosphere?
1 atm = 14.696 psi = 101,325 Pa = 1.01325 bar. This is standard sea-level air pressure — which is why the bar (exactly 100,000 Pa) was designed as a convenient "almost one atmosphere" unit.
What is normal blood pressure in these units?
Blood pressure is measured in mmHg: a healthy reading of 120/80 mmHg equals about 16.0/10.7 kPa. 1 mmHg = 133.322 Pa, a legacy of mercury-column instruments.
How much pressure is 10 metres of water?
Each 10 m of water depth adds roughly 1 bar (0.981 bar exactly for fresh water). So a diver at 30 m experiences about 4 atm total — 1 atm of air plus 3 bar of water.