Pressure Converter
Convert any pressure — SI, metric, US customary or vacuum/weather units. Pascals, bar, psi, atmospheres, mmHg, torr, inHg, ksi.
1 Bar =
14.5
Converted via 100000 Pa per bar and 6894.757293168 Pa per psi. 1 bar = 100 000 Pa exactly; 1 atm = 101 325 Pa exactly; 1 psi = 6894.757 293 168 Pa under the 1959 yard and pound agreement.
How to use this calculator
Enter a value, choose your starting unit from "From", then pick the target unit in "To". Results update instantly. Use bar or psi for tyres, kPa or hPa for weather, mmHg or inHg for blood pressure and barometers, MPa or ksi for engineering stress.
How the calculation works
Every unit converts via a single intermediate value in pascals (Pa = N/m²). Factors are exact under the SI definitions: 1 bar = 100 000 Pa (BIPM/IUPAC), 1 atm = 101 325 Pa (10th CGPM, 1954), 1 torr = 1/760 atm. The psi factor (6894.757 293 168 Pa) derives from 1 lbf = 4.448 221 615 260 5 N and 1 in² = 0.000 645 16 m² under the 1959 International Yard and Pound Agreement.
Worked example
32 psi (typical car tyre) → bar: 32 × 6894.757 293 168 Pa/psi = 220 632.23 Pa ÷ 100 000 Pa/bar ≈ 2.2063 bar. → kPa: ÷1000 ≈ 220.63 kPa.
Frequently asked questions
Are bar and atmosphere the same?
Almost, but not exactly. 1 bar = 100 000 Pa exactly. 1 standard atmosphere = 101 325 Pa exactly. So 1 atm ≈ 1.01325 bar — atmosphere is about 1.3% larger. Most weather reports and tyre pressure gauges use bar (or hPa), while older barometers and some scientific work use atm.
How many psi is 1 bar?
1 bar ≈ 14.5038 psi. The exact value is 100 000 ÷ 6894.757 293 168 = 14.503 773 773 022 1 psi. So a tyre inflated to 2 bar is about 29 psi, and 2.2 bar is about 32 psi.
What is the difference between torr and mmHg?
They are very close but not identical. 1 torr is defined as exactly 1/760 of a standard atmosphere (133.322 368 421… Pa). 1 conventional mmHg uses a fixed mercury density and standard gravity, giving 133.322 387 415 Pa exactly. The two agree to about 7 significant figures — close enough that they are interchangeable for almost all medical, vacuum and weather uses.
Why does my tyre gauge read different from the pump?
Most tyre gauges read gauge pressure (above atmospheric), while some scientific instruments read absolute pressure (above vacuum). Absolute pressure = gauge pressure + ~1 atm (~14.7 psi or ~1.013 bar). This converter treats whatever number you enter as a value in the unit you choose — it does not add or subtract atmospheric pressure. If you need absolute pressure from a gauge reading, add ~14.7 psi or ~1.013 bar yourself.
What is a hectopascal (hPa) and why does it appear on weather maps?
1 hPa = 100 Pa = 1 millibar exactly. The World Meteorological Organization adopted hPa as the SI-aligned replacement for the millibar, but the numbers are identical, so a weather map showing 1013 hPa and one showing 1013 mbar mean the same thing. Standard sea-level pressure is 1013.25 hPa.
Is psi or kPa more common for tyres?
Depends on the country. The US, UK and most of the English-speaking world use psi on tyre placards. Continental Europe and Japan use bar, and increasingly kPa (especially on newer cars and TPMS systems). 32 psi ≈ 2.2 bar ≈ 220 kPa — all three describe the same pressure.