Pressure converter
Convert bar to psi, kPa, MPa, atmospheres, torr, mmHg and inHg — for tyre pressures, blood pressure, weather and engineering work.
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1 bar = 14.503773773 psi
Automatic formatting keeps up to 12 significant digits and switches to scientific notation only for numbers past 10¹⁸ or below 10⁻⁹. You can paste values with thousands separators, and fractions such as 3/4 or 1 1/2 are understood too.
psi = bar × 14.503773773
Your value: 1 × 14.503773773 = 14.503773773 psi
Bar: Exactly 100 kPa — close to one atmosphere.
Pound per square inch: Tyre pressure in the US and UK.
- bar → psi1 = 14.503773773
- psi → bar1 = 0.0689475729317
- kPa → psi1 = 0.14503773773
- psi → kPa1 = 6.89475729317
- bar → kPa1 = 100
- atm → psi1 = 14.6959487755
- mmHg → kPa1 = 0.133322387415
- hPa → inHg1 = 0.029529983301
- MPa → psi1 = 145.03773773
- atm → bar1 = 1.01325
- Torr → Pa1 = 133.322368421
- psi → atm1 = 0.0680459639099
| bar | psi |
|---|---|
| 1 | 14.503773773 |
| 2 | 29.007547546 |
| 5 | 72.5188688651 |
| 10 | 145.03773773 |
| 20 | 290.07547546 |
| 30 | 435.113213191 |
| 32 | 464.120760737 |
| 35 | 507.632082056 |
| 40 | 580.150950921 |
| 50 | 725.188688651 |
| 100 | 1,450.3773773 |
| 1,000 | 14,503.773773 |
| psi | bar |
|---|---|
| 1 | 0.0689475729317 |
| 2 | 0.137895145863 |
| 5 | 0.344737864658 |
| 10 | 0.689475729317 |
| 20 | 1.37895145863 |
| 30 | 2.06842718795 |
| 32 | 2.20632233381 |
| 35 | 2.41316505261 |
| 40 | 2.75790291727 |
| 50 | 3.44737864658 |
| 100 | 6.89475729317 |
| 1,000 | 68.9475729317 |
| Unit | Symbol | Value in Pa | Notes |
|---|---|---|---|
| PascalSI | Pa | 1 Pa = 1 Pa | One newton per square metre. |
| HectopascalSI | hPa | 1 hPa = 100 Pa | The weather-forecast unit; identical to the millibar. |
| KilopascalSI | kPa | 1 kPa = 1,000 Pa | — |
| MegapascalSI | MPa | 1 MPa = 1,000,000 Pa | Also written N/mm² in engineering. |
| BarMetric practical | bar | 1 bar = 100,000 Pa | Exactly 100 kPa — close to one atmosphere. |
| MillibarMetric practical | mbar | 1 mbar = 100 Pa | — |
| Pound per square inchImperial / US | psi | 1 psi = 6,894.75729317 Pa | Tyre pressure in the US and UK. |
| Standard atmosphereReference | atm | 1 atm = 101,325 Pa | Exactly 101,325 Pa by definition. |
| TorrReference | Torr | 1 Torr = 133.322368421 Pa | Exactly 1⁄760 atm — vacuum work. |
| Millimetre of mercuryReference | mmHg | 1 mmHg = 133.322387415 Pa | Blood pressure. Within 0.000015 % of a torr. |
| Inch of mercuryReference | inHg | 1 inHg = 3,386.38864034 Pa | US altimeter and barometer setting. |
| Metre of waterReference | mH₂O | 1 mH₂O = 9,806.65 Pa | Pump head and hydrostatic pressure. |
How to convert a pressure
- Type into either box. Bar to psi and psi to bar are the same control worked in either direction.
- Choose from the SI units, the practical metric units, psi, or the reference units used in weather, vacuum and medicine.
- The chart underneath runs a whole column of values, which is quicker than converting a tyre placard one figure at a time.
Tyre pressures, the most common reason to be here
Car door placards are printed in psi in the US and UK, and in bar or kPa almost everywhere else. The conversion is 1 bar = 14.5038 psi = 100 kPa. Getting it wrong by a factor of ten — confusing 220 kPa with 22 psi — is a real risk, so here is the range you will actually meet:
| psi | bar | kPa | Typical use |
|---|---|---|---|
| 28 | 1.93 | 193 | Small car, lightly loaded |
| 32 | 2.21 | 221 | Most passenger cars |
| 35 | 2.41 | 241 | Passenger car, fully loaded |
| 44 | 3.03 | 303 | Small van |
| 80 | 5.52 | 552 | Light truck rear axle |
| 100 | 6.89 | 689 | Road bicycle tyre |
One thing no converter can fix: placard pressures are cold pressures. Driving heats the air and raises the reading by roughly 3 psi, so check before you set off, not after.
Which factors are exact
The pascal is the SI unit — one newton per square metre — and everything metric is an exact multiple of it. A bar is exactly 100,000 Pa, a hectopascal exactly 100 Pa, and a millibar is exactly the same size as a hectopascal, which is why meteorologists switched labels without changing any numbers. The standard atmosphere is defined as exactly 101,325 Pa, and the torr as exactly one 760th of that.
The psi follows from the exact pound and inch: 6,894.757293168361 Pa. The millimetre of mercury is defined from a specified mercury density and standard gravity, giving 133.322387415 Pa, which differs from a torr by about one part in seven million — a difference no blood-pressure cuff has ever noticed.
Gauge pressure versus absolute pressure
Most instruments read gauge pressure: the amount above the surrounding air. A tyre gauge showing 32 psi means 32 psi more than atmospheric, so the absolute pressure inside the tyre is about 46.7 psi. US engineering writes this as psig for gauge and psia for absolute.
A unit converter cannot tell which one you have, because gauge and absolute use identical units — the difference is the reference point, not the scale. If you are mixing a weather reading (absolute) with an equipment reading (gauge), add or subtract one atmosphere: 101.325 kPa, 1.01325 bar, or 14.696 psi.
Reference: pressures worth knowing
| Situation | Pressure |
|---|---|
| Sea-level standard atmosphere | 1 atm = 101.325 kPa = 14.696 psi = 1,013.25 hPa |
| Typical high-pressure weather system | 1,030 hPa |
| Deep low / severe storm | 950 hPa |
| Healthy blood pressure | 120/80 mmHg = 16.0/10.7 kPa |
| Espresso machine brew pressure | 9 bar = 130.5 psi |
| Domestic mains water | 2–5 bar = 29–73 psi |
| Ten metres under water | 1 extra atm, so about 2 atm absolute |
Questions
How many psi are in a bar?
14.5038 psi. Car tyres are the usual reason people ask: 2.2 bar is 32 psi, and 2.5 bar is 36 psi.
Is 1 bar the same as 1 atmosphere?
Almost. A bar is exactly 100 kPa; a standard atmosphere is 101.325 kPa, so an atmosphere is 1.325 % larger. Weather reports use hectopascals, which equal millibars exactly.
Why is blood pressure measured in mmHg?
Because the original instrument was a column of mercury, and a reading of 120 meant the pressure raised the column 120 mm. The unit stayed even though the mercury mostly has not.
What is the difference between torr and mmHg?
A torr is exactly 1⁄760 of an atmosphere, and a millimetre of mercury is 133.322387415 Pa. They differ by about one part in seven million — irrelevant outside metrology.