Pressure Converter
Convert between Pascals, bar, PSI, atmospheres, Torr, and inches of mercury.
How pressure conversion works
Every pressure unit here converts through the Pascal (Pa) — the SI base unit of pressure, defined as one newton of force per square meter. Units like PSI, bar, and atmospheres were each defined independently by different industries and countries, which is why the conversion factors between them look so irregular rather than round numbers.
Common conversions
- 1 atmosphere ≈ 14.696 PSI ≈ 1.01325 bar ≈ 101,325 Pa
- 1 bar = 100,000 Pa = 100 kPa
- Standard car tire pressure is often around 30–35 PSI (about 2–2.4 bar)
- 1 Torr ≈ 1 mmHg, historically defined from mercury barometer readings
Frequently asked questions
What's the difference between bar and atmosphere?
They're very close but not identical: 1 bar = 100,000 Pa exactly, while 1 standard atmosphere = 101,325 Pa. The difference (about 1.3%) rarely matters for everyday use like tire pressure, but it isn't zero.
Why is PSI still common in the US?
PSI (pounds per square inch) comes from the imperial measurement system, which the US still uses for most everyday and automotive contexts — tire pressure gauges, plumbing ratings, and weather reports in the US typically use PSI or inches of mercury rather than the metric Pascal or bar.