Pressure Converter
PSI · Bar · Pascal · Atm · mmHg · Torr
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Pressure Quick Reference
Standard atmospheric pressure at sea level is 101,325 Pa = 1 atm = 1.01325 bar = 14.696 PSI = 760 mmHg. These exact relationships are defined by international standards.
| Reference Point | PSI | Bar | kPa |
|---|---|---|---|
| Standard atmosphere | 14.696 | 1.01325 | 101.325 |
| Car tyre (typical) | 32–35 | 2.2–2.4 | 220–241 |
| Blood pressure (systolic) | 1.74 | 0.12 | 16 |
| Deep sea (1,000 m) | 1,450 | 100 | 10,000 |
| Everest summit (8,848 m) | 4.9 | 0.34 | 33.7 |
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Pressure Questions
How do I convert PSI to bar?+
Multiply PSI by 0.0689476 to get bar. Example: 30 PSI = 2.07 bar. To go the other way, multiply bar by 14.5038. Car tyres are typically 30–35 PSI (2.07–2.41 bar). Bicycle tyres range from 80–120 PSI (5.5–8.3 bar) for road bikes.
What is 1 atmosphere in PSI and bar?+
Standard atmosphere (atm) = 14.696 PSI = 1.01325 bar = 101,325 Pa = 760 mmHg. It represents average sea-level air pressure. Note: 1 bar is not exactly 1 atm — they differ by about 1.3%. Meteorologists use millibar (mbar) or hectopascal (hPa): 1 bar = 1,000 mbar = 1,000 hPa.
What is the difference between PSI and kPa?+
PSI (pounds per square inch) is used in the US and UK for tyres, hydraulics and gas. kPa (kilopascal) is the SI metric unit: 1 PSI = 6.89476 kPa. Tyre pressure in Europe is shown in bar or kPa. A typical car tyre at 32 PSI = 220.6 kPa = 2.21 bar.
What is mmHg and when is it used?+
mmHg (millimeters of mercury) is used in medicine for blood pressure and in meteorology. 1 mmHg = 133.322 Pa = 0.0193368 PSI. Normal blood pressure is 120/80 mmHg. 1 mmHg = 1 torr, named after Evangelista Torricelli, inventor of the barometer.
How do you convert bar to Pa?+
1 bar = 100,000 Pa = 100 kPa. The pascal is the SI unit of pressure (1 N/m²). Standard atmospheric pressure is 101,325 Pa = 1.01325 bar. In engineering: 1 MPa = 10 bar = 145.04 PSI, used for concrete strength and high-pressure hydraulics.
What is vacuum pressure?+
Vacuum is pressure below atmospheric. Perfect vacuum = 0 Pa absolute. Gauge pressure measures relative to atmosphere. A household vacuum cleaner creates about −20 kPa gauge (−2.9 PSI). Industrial vacuum systems reach −99 kPa gauge. Medical suction is typically −40 to −80 kPa gauge.
How does pressure change with altitude?+
Pressure drops roughly 12 Pa per meter at sea level, following an exponential curve. At 5,500 m altitude, pressure is about half sea-level (50 kPa). At Everest summit (8,848 m): ~33.7 kPa = 4.9 PSI = 0.33 atm. Commercial aircraft cabins are pressurised to about 75 kPa (equivalent ~2,400 m).
What pressure is used for scuba diving?+
Scuba tanks are filled to 200–300 bar (2,900–4,350 PSI). Ambient water pressure increases by 1 bar per 10 meters depth. At 30 m: 4 bar absolute. This is why divers must not hold their breath while ascending — expanding gas can cause lung over-expansion injury.
What is the difference between absolute and gauge pressure?+
Absolute pressure is measured from perfect vacuum. Gauge pressure is relative to local atmospheric pressure. A car tyre at 32 PSI gauge = 46.7 PSI absolute. Most everyday measurements (tyres, blood pressure, gas lines) use gauge pressure. Scientific measurements use absolute.
What pressure unit do weather forecasters use?+
Meteorologists use hectopascal (hPa), equal to millibar. Standard sea-level pressure = 1,013.25 hPa. Low pressure (storms): below 1,000 hPa. High pressure (fair weather): above 1,020 hPa. The most powerful hurricane recorded (Wilma, 2005) had a central pressure of 882 hPa.