Convert between pressure units easily.
Tires, weather maps, labs, and scuba gear reuse the word “pressure” with different zero points—know which reference you mean.
Internal math normalizes through Pascal for all 8 units.
The numbers are neutral: they only translate between unit names. Tire gauges and shop compressors usually quote gauge pressure (relative to atmosphere). Altitude, weather, and vacuum systems often use absolute pressure. Add or subtract ~1 atm when you need to move between conventions—know which reference your source already uses.
Under standard definitions used in conversion tables, one millimeter of mercury and one Torr are treated as the same pressure increment (both tied to the mercury column idea). For rough work they are interchangeable; for metrology papers, cite the standard your lab follows.
One bar is defined as exactly 100,000 Pa—handy round number for engineering. One standard atmosphere is ~101,325 Pa. Weather maps often use hectopascals (hPa), which are kilopascals without the prefix confusion. Bars show up on European tire pumps and industrial pneumatics.
Jump to the master unit list when you leave pressure behind.
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Looking for something else?
Browse all toolsType the pressure number to convert. Very small values (mbar for weather) and very large values (MPa for hydraulic systems) are both supported.
Choose: Pa, kPa, MPa, bar, mbar, psi, atm, torr, or mmHg.
All equivalents display instantly. A reference panel shows typical pressures for context: atmosphere, car tyre, blood pressure, hydraulic press.
Input
32 psi (car tyre)Output
2.206 bar · 220.6 kPa · 0.2179 atmUS tyre inflation stickers use psi; European tyre gauges often use bar. A typical car tyre at 32 psi = 2.2 bar. Most European tyre pressure gauges are graduated in bar.
Input
120 mmHg (systolic blood pressure)Output
15,998 Pa ≈ 16 kPa · 0.158 atm · 2.32 psiBlood pressure is universally measured in mmHg. 120/80 mmHg is the normal reference. The mmHg unit originates from mercury manometer instruments — 1 mmHg = 133.322 Pa.
Common real-world scenarios where this tool saves time.
Automotive technicians and drivers
US vehicles specify tyre pressure in psi; European vehicles use bar (and sometimes kPa). Correct tyre inflation improves fuel economy, tyre life, and handling — accurate conversion matters.
Meteorologists and weather enthusiasts
Weather reports use hPa (= mbar) internationally and inches of mercury (inHg) in the US. Standard atmospheric pressure: 1013.25 hPa = 29.92 inHg = 14.696 psi.
Engineers and industrial technicians
Hydraulic systems often specify pressure in bar or MPa; some components are rated in psi. Accurate pressure conversion prevents over-pressurising components rated in a different unit system.
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1 bar = 14.5038 psi. 1 psi = 0.0689476 bar. Common tyre pressures: 30 psi = 2.068 bar, 35 psi = 2.413 bar, 40 psi = 2.758 bar.
1 standard atmosphere (atm) = 101,325 Pa = 101.325 kPa = 1.01325 bar = 14.696 psi = 760 mmHg = 760 torr = 1013.25 hPa (millibars). This is the defined standard used in physics and engineering reference conditions.
1 bar = 1,000 millibar (mbar). 1 mbar = 1 hPa (hectopascal). Weather forecasts use millibars or hectopascals interchangeably — they are numerically identical. Standard atmospheric pressure ≈ 1013 mbar = 1013 hPa.
Blood pressure is measured in millimetres of mercury (mmHg). A normal reading of 120/80 mmHg means 120 mmHg systolic (heart contracting) and 80 mmHg diastolic (heart relaxing). In SI: 120 mmHg ≈ 16,000 Pa ≈ 16 kPa.
Absolute pressure is measured from perfect vacuum (0 Pa). Gauge pressure is measured relative to atmospheric pressure. Tyre pressure gauges read gauge pressure: a '32 psi' tyre reading means 32 psi above atmospheric = 46.7 psi absolute. Engineers specify which reference is used as 'psig' (gauge) vs. 'psia' (absolute).
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Reviewed by EverydayTools Editorial Team.