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14 units — psi, bar, atm, pascal, mmHg, inHg, and more
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| Unit | Symbol | Category | 1 Unit = (in Pa) |
|---|---|---|---|
| Pascal | Pa | Metric (SI base) | 1 |
| Hectopascal | hPa | Metric (SI) | 100 |
| Kilopascal | kPa | Metric (SI) | 1,000 |
| Megapascal | MPa | Metric (SI) | 1,000,000 |
| PSI (lb/in²) | psi | Imperial / US | 6,894.76 |
| KSI (kip/in²) | ksi | Imperial | 6,894,757 |
| Inch of Mercury | inHg | Imperial / Aviation | 3,386.39 |
| Foot of Water | ftH₂O | Imperial | 2,989.07 |
| Bar | bar | Metric legacy | 100,000 |
| Millibar | mbar | Metric legacy | 100 |
| Atmosphere | atm | Standard reference | 101,325 |
| mmHg / Torr | mmHg | Medical / Vacuum | 133.322 |
| Technical Atmosphere | at | Metric legacy | 98,066.5 |
| cm of Water | cmH₂O | Medical | 98.0665 |
| Scenario | Typical Unit | Typical Range | Conversion Reference |
|---|---|---|---|
| Car tire pressure | psi / bar | 30-35 psi (2.0-2.4 bar) | 35 psi = 2.41 bar = 241 kPa |
| Road bike tire | psi / bar | 80-130 psi (5.5-9.0 bar) | 100 psi = 6.89 bar |
| Truck/SUV tire | psi / bar | 50-80 psi (3.4-5.5 bar) | 65 psi = 4.48 bar |
| Blood pressure | mmHg | 90/60 to 140/90 mmHg | 120 mmHg = 16.0 kPa |
| Weather / barometer | hPa / inHg | 980-1040 hPa | 1013 hPa = 29.92 inHg |
| SCUBA tank | bar / psi | 200-300 bar (3,000-4,500 psi) | 200 bar = 2,900 psi |
| SCUBA depth | atm / bar | +1 atm per 10 m depth | 30 m = 4 atm = 4.04 bar |
| Industrial hydraulic | MPa / bar | 10-70 MPa (100-700 bar) | 20 MPa = 200 bar = 2,900 psi |
| Vacuum technology | Pa / Torr / mbar | 10⁻⁸ to 10⁵ Pa | 1 Torr = 1 mmHg = 133 Pa |
Three units all approximate "normal air pressure at sea level" but differ by up to 3%: 1 atm = 101,325 Pa (the standard atmosphere, defined by international agreement). 1 bar = 100,000 Pa (a convenient round metric number — popular in Europe for everything from tires to weather). 1 technical atmosphere (at) = 98,066.5 Pa = 1 kgf/cm² (a now-obsolete metric unit that lingers on older European pressure gauges). The 1.3% difference between atm and bar, and the 3.3% difference between atm and at, mattered enough to engineers that they kept all three in service. Meteorologists standardized on the millibar (mbar) — which equals the hectopascal (hPa) exactly — in 1914. Today, weather maps worldwide use hPa, but aviation still uses inHg in the US and hPa elsewhere. This converter shows all of them so you can decode any pressure specification in any unit system.
Enter your value in the PSI field. 1 PSI = 0.06895 bar. 1 bar = 14.504 PSI. Car tires: 35 PSI = 2.41 bar. Road bike: 100 PSI = 6.89 bar. Quick rule: divide PSI by 14.5 to get approximate bar.
Blood pressure: mmHg worldwide (120/80 mmHg = systolic/diastolic). Weather: hPa (hectopascals) globally, or inHg in the US. Standard sea-level = 1013.25 hPa = 29.92 inHg = 760 mmHg = 1 atm. All four are in this converter's grid.
Car: 30-35 PSI = 2.07-2.41 bar. Bike: 80-130 PSI = 5.5-9.0 bar. European cars specify in bar, US cars in PSI. Most tire gauges show both. Use the PSI field and read the Bar output. See the scenario table above for common ranges.
Surface: 1 atm (14.7 PSI, 1.013 bar). Every 10 m (33 ft) of seawater adds ~1 atm. At 30 m: 4 atm total — a diver breathes air at 4× surface density. The Titanic at 3,800 m: ~381 atm (5,600 PSI). This converter handles the full range from vacuum to industrial pressures.
1 atm = 101,325 Pa (standard atmospheric pressure). 1 bar = 100,000 Pa (~1.3% less). 1 at (technical atmosphere) = 98,067 Pa (~3.3% less). All three are "about one atmosphere" — close enough for rough estimates, different enough to matter in engineering. The converter shows all three simultaneously.