Pressure Converter (bar, psi, kPa, atm…)
Convert pressure between bar, psi, pascal, kPa, MPa, atmosphere, Torr / mmHg, inHg, and kgf/cm² — enter one value and see it in every unit, with a reference table.
Pressure conversion reference
| 1 unit | Pa | kPa | bar | psi | atm |
|---|---|---|---|---|---|
| 1 Pa | 1 | 0.001 | 0.00001 | 0.000145038 | 0.00000986923 |
| 1 hPa | 100 | 0.1 | 0.001 | 0.0145038 | 0.000986923 |
| 1 kPa | 1 000 | 1 | 0.01 | 0.145038 | 0.00986923 |
| 1 MPa | 1 000 000 | 1 000 | 10 | 145.038 | 9.86923 |
| 1 bar | 100 000 | 100 | 1 | 14.5038 | 0.986923 |
| 1 psi | 6 894.76 | 6.89476 | 0.0689476 | 1 | 0.068046 |
| 1 atm | 101 325 | 101.325 | 1.01325 | 14.6959 | 1 |
| 1 Torr | 133.322 | 0.133322 | 0.00133322 | 0.0193368 | 0.00131579 |
| 1 inHg | 3 386.39 | 3.38639 | 0.0338639 | 0.491154 | 0.0334211 |
| 1 kgf/cm² | 98 066.5 | 98.0665 | 0.980665 | 14.2233 | 0.967841 |
Converting pressure units
Pressure is force spread over an area, and it's measured in a confusing number of units because different fields settled on different ones. This converter expresses them all through the SI unit, thepascal (one newton per square metre), so any value can be turned into any other exactly. Enter a value and its unit and every other unit updates at once.
The units, and where you meet them
The bar and its millibar / hectopascalare common in European engineering and weather; psi(pounds per square inch) dominates in the US and in tyres and pneumatics;kPa and MPa are the SI choices for gauges and material specs. The atmosphere is roughly average sea-level air pressure, while Torr / mmHg and inHg come from mercury columns and survive in vacuum work, medicine, and barometers.
Worked example and a landmark to remember
A car tyre at 33 psi is 33 × 6894.76 ≈ 227.5 kPa, or about 2.28 bar. The handiest landmark is standard atmospheric pressure, which is 1 atm = 101 325 Pa = 1.01325 bar ≈ 14.70 psi = 760 Torr. Because 1 bar (100 kPa) is so close to 1 atm, people often treat them as equal — fine for rough work, but they differ by about 1.3%, which the reference table above makes exact.
Gauge vs absolute pressure
One thing a converter can't know is your reference point. A tyre gauge readsgauge pressure — pressure above the surrounding air — so a "33 psi" tyre is actually about 47.7 psi absolute. Unit conversion doesn't change that; if you need absolute pressure, add the local atmospheric pressure first, then convert.
Common questions
- How many psi is one bar?
- About 14.504 psi. A bar is defined as exactly 100,000 pascals, which makes it very close to — but not the same as — one atmosphere. That near-miss is deliberate: the bar was chosen as a round metric figure of roughly atmospheric size.
- What is the difference between bar and atmosphere?
- One standard atmosphere is 101,325 Pa, and one bar is exactly 100,000 Pa — so an atmosphere is about 1.3% larger. The difference rarely matters for a tyre but very much does in laboratory or process work, where quoting 1 atm when you meant 1 bar is a real error. Where precision counts, use pascals and avoid both.
- What is the difference between gauge and absolute pressure?
- Gauge pressure (psig, barg) is measured relative to the surrounding air; absolute pressure (psia, bara) is measured from a vacuum. They differ by one atmosphere, so a tyre reading 32 psig is at about 46.7 psia. Most everyday gauges — tyres, boilers, compressors — read gauge, which is why a fully deflated tyre reads zero rather than 14.7. This converter handles the units, not the offset, so decide which convention you are in before converting.
- Why is blood pressure measured in millimetres of mercury?
- Because the original instrument was literally a column of mercury, and the height it rose was the reading. The unit survived the instrument: 120 mmHg means the pressure that would raise mercury 120 mm, about 16 kPa. Several fields keep such units for the same historical reason — inches of water for ventilation, and inches of mercury in aviation altimetry.