Pressure Converter
Pressure converter for pascals, kPa, bar, psi, kgf/cm2 and inches of mercury, with the gauge versus absolute distinction explained rather than glossed over.
Most used pressure tools
kPa to PSI
The main tool, framed around tire pressure with the common placard values worked out.
Newtons to Pounds
Force, which pressure is force spread over an area.
Nm to Ft-Lbs
The other figure on the same job sheet.
Convert every unit at once
Enter a number.
Every pressure converter on this site
Reference table
| Unit | In pascals | Exact? |
|---|---|---|
| 1 kilopascal | 1000 Pa | Exact |
| 1 bar | 100000 Pa | Exact |
| 1 standard atmosphere | 101325 Pa | Exact |
| 1 psi | 6894.757 Pa | Rounded |
| 1 torr | 133.322 Pa | Rounded, 1/760 atm |
| 1 inch of mercury | 3386.389 Pa | Rounded |
Gauge pressure and absolute pressure
This is the distinction that causes real errors, and most converters ignore it. A tire gauge reads gauge pressure, the amount above the surrounding air. An absolute reading includes atmospheric pressure as well, so it is about 14.7 psi or 101 kPa higher at sea level.
Converting a unit doesn't convert between gauge and absolute. If a spec says psia or bara it means absolute; psig or barg means gauge. An unlabelled tire or hydraulic figure is almost always gauge.
Where each unit is used
Kilopascals appear on vehicle placards outside North America and in engineering. Bar is common in European automotive and hydraulic work. PSI dominates in the United States. Atmospheres, torr and inches of mercury turn up in laboratory, vacuum and meteorological contexts respectively.
Common questions
What is the difference between gauge and absolute pressure?
Gauge pressure is measured relative to the surrounding air, which is what a tire gauge reads. Absolute pressure includes atmospheric pressure as well, so it is about 14.7 psi or 101 kPa higher at sea level. Converting a unit doesn't convert between the two.
What does psig or psia mean?
The g stands for gauge and the a for absolute. An unlabelled tire or hydraulic figure is almost always gauge pressure.
Is one bar the same as one atmosphere?
Close but not the same. One bar is exactly 100,000 pascals. One standard atmosphere is exactly 101,325 pascals, about 1.3 percent higher.
Which pressure unit is used where?
Kilopascals on vehicle placards outside North America and in engineering, bar in European automotive and hydraulic work, psi in the United States, and torr or inches of mercury in vacuum and meteorological contexts.
Sources
- NIST Guide to the SI, Appendix B: Conversion Factors. National Institute of Standards and Technology. Source for every conversion factor used by this tool, and for which factors are exact rather than rounded.