This pressure converter translates between the eight pressure units science and industry actually use — Pa, kPa, MPa, bar, atm, psi, torr and inHg — all from one entry.

Every Unit Anchors to the Pascal — Definitions, Not Folklore

1 atm is exactly 101,325 Pa by definition; the bar is exactly 10⁵ Pa; psi is defined via the pound and inch. The force-per-area physics lives on our Pressure Calculator. Part of our Conversion Calculators collection.

Anchor Conversions (Verified)

  • 1 atm = 14.696 psi = 1.01325 bar = 760.0 torr = 101.325 kPa — the reference row every table on the internet copies
  • Tire talk: 32 psi = 2.21 bar = 220.6 kPa — three numbers on one door-jamb sticker, finally reconciled
  • Weather maps: standard sea-level 29.92 inHg = 1 atm; storms and hurricanes read in the millibar (hPa = 0.01 bar… precisely, 1 hPa = 100 Pa) dialect of the same family
  • Gauge vs absolute: gauges read zero at atmospheric pressure — a “0 psi” tire gauge means 14.7 psia; vacuum work and altitude physics need the absolute dialect

Unit Cultures

  • psi: US tires, hydraulics, scuba (tank pressure). bar: European everything, espresso (9 bar), diving. kPa/MPa: engineering SI and medicine’s neighbor (mmHg refuses to retire from blood pressure: 120/80 mmHg = 16.0/10.7 kPa).
  • Torr = mmHg by near-exact definition (they differ at the 7th digit) — vacuum science’s home unit.
  • Altitude thins the atmosphere ~1 inHg per 1,000 ft near sea level — aviation altimeters are pressure converters with needles.

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Frequently Asked Questions

How many psi is 1 atmosphere?

14.696 psi. One atmosphere is exactly 101,325 Pa, and 1 psi = 6,894.757 Pa, so 101,325 ÷ 6,894.757 = 14.696. This converter shows all eight units from any single entry.

What is the difference between bar and atm?

The bar is exactly 100,000 Pa (chosen for roundness); the atmosphere is 101,325 Pa (chosen from physical sea-level air) — they differ by 1.3%. Weather “millibars” and hectopascals are interchangeable (1 mbar = 1 hPa).

Is mmHg the same as torr?

For every practical purpose, yes: 1 torr is defined as 1/760 atm and 1 mmHg as 133.322 Pa; they agree to seven significant figures. Medicine keeps mmHg; vacuum physics keeps torr.

What does gauge pressure mean?

Pressure measured relative to the surrounding atmosphere: psig = psia − 14.696 (at sea level). Tire gauges, pressure washers and most industrial gauges read gauge; weather, aviation and gas-law physics use absolute. Converting between them is addition, not a unit change.

How do I convert blood pressure to kPa?

Multiply mmHg by 0.133322: 120/80 mmHg → 16.0/10.7 kPa. Much of the world outside US/UK clinical practice already charts it that way; this converter treats torr/mmHg as the same entry.

Is this pressure converter free?

Yes — free, instant, no sign-up.