Pressure Converter
Convert pressure values fast, between pascals, kilopascals, bar, millibar, atmospheres, torr, mmHg, inHg, and PSI. Great for labs and tyres.
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What this converter does
Pressure is one quantity with a different favourite unit in nearly every field: psi for tyres, bar for industry, millibars for the weather, millimetres of mercury for blood pressure. This converter ties them all together, with the pascal as the common thread.
How to use it
- Type your pressure value into the value box.
- Set From to the unit you have, and To to the unit you want.
- Press Calculate.
The result reads back in plain words, like "1 atm is equal to 14.6959 psi." Use Swap to flip the two units, and Reset to clear.
How it works
Every unit is tied to the pascal. Your value is converted to pascals and then to the target unit. Most factors are standard or defined values, though a few of the mercury-based units (mmHg, inHg) are conventional, so treat those as accurate for everyday use. Displayed results are rounded to nine significant figures.
Common pressure conversions
The ones that come up most:
| Conversion | Value |
|---|---|
| 1 atmosphere (atm) | 101,325 Pa (14.696 psi) |
| 1 bar | 100,000 Pa (100 kPa) |
| 1 psi | 6,894.76 Pa (about 6.9 kPa) |
| 1 atmosphere | 1.013 bar (760 mmHg) |
| 1 bar | about 14.5 psi |
| 1 kilopascal (kPa) | 1,000 Pa (about 0.145 psi) |
One atmosphere, and the units each field uses
One pressure ties almost everything together: standard atmospheric pressure, the weight of the air at sea level. It is the same pressure written six different ways.
- 1 atm = 101,325 pascals = 101.325 kPa
- = 1.01325 bar = 1,013.25 millibars (hectopascals)
- = 14.696 psi
- = 760 mmHg = 29.92 inches of mercury
Why so many units? Because different fields settled on different ones and never let go.
- Tyres and compressors use psi in the US and bar across much of the rest of the world. A car tyre sits around 32 to 35 psi, which is roughly 2.2 to 2.4 bar.
- Weather uses millibars, also written as hectopascals, plus atmospheres and inches of mercury on US barometers. A reading near 1,013 hPa is a normal day.
- Blood pressure is quoted in millimetres of mercury everywhere, which is why a healthy reading looks like 120 over 80 mmHg.
- Science and engineering lean on the pascal and kilopascal, the clean SI choices.
One small note: the pascal and the newton per square metre are the very same unit under two names, since a pascal is defined as one newton spread over one square metre.
Questions people ask
What is standard atmospheric pressure?
One atmosphere, which is 101,325 pascals. The same pressure is 14.696 psi, 1.013 bar, 760 mmHg, or 29.92 inches of mercury, and it is roughly the air pressure at sea level.
How do I convert psi to bar?
Multiply psi by about 0.069, or divide by 14.5. One bar is about 14.5 psi, so a 30 psi tyre is roughly 2.07 bar.
What pressure should my car tyres be?
Most cars run around 32 to 35 psi, which is about 2.2 to 2.4 bar, but the exact figure is on the sticker inside the driver's door or in the manual. This tool is handy for switching between psi and bar when your gauge uses one and the label uses the other.
Why is blood pressure measured in mmHg?
Because early blood pressure gauges used a column of mercury, and the millimetre-of-mercury unit stuck. That is why a reading is written as a pair, like 120 over 80 mmHg.
Is a pascal the same as a newton per square metre?
Yes, exactly. One pascal is defined as one newton of force spread over one square metre, so the two units are identical.
References
- National Institute of Standards and Technology (NIST), Office of Weights and Measures. The International System of Units (SI) and the pascal. https://www.nist.gov/pml/owm/metric-si/si-units
Okan Atalay is a results driven senior operations manager and a graduate of Industrial Engineering from Bilkent University. With over 22 years of experience in textile manufacturing and integrated operations, he has led large scale business process improvements and strategic planning initiatives. Currently, he serves as a top mathematics expert for a global ed tech platform, where he applies his analytical expertise to solve complex mathematical problems. At Eon Tools, he reviews converter and maths tools.