A pressure converter moves a value between the many units engineers, drivers, doctors and weather forecasters use: pascals and kPa in SI, bar in industry, psi in the US, atmospheres in science, and mmHg in medicine. It converts your value into a base unit — pascals — and back out. The one thing it does not do is change the reference frame: gauge vs absolute pressure is a separate adjustment, so a tyre gauge reading (gauge) isn't the same as absolute pressure.
Reviewed: June 20, 2026 · Author: Naveen P N, Founder — AI Calculator · Verified against: NIST/SI pressure factors, recomputed in code.
How the conversion works
Each unit equals a fixed number of pascals: a bar is 100,000 Pa, a psi 6894.757 Pa, an atmosphere 101,325 Pa, and a millimetre of mercury 133.322 Pa. Multiply your value by the "from" unit's pascals-per-unit to reach pascals, then divide by the "to" unit's. Note the close-but-different bar and atmosphere (1 atm = 1.01325 bar) — mixing them up is a classic small error.
Worked example — 1 bar across the units
Scenario: convert 1 bar to other pressure units.
One bar is 100,000 Pa (100 kPa), 14.5038 psi, or 0.986923 atm — just under one atmosphere. The everyday cases follow the same rule: a tyre at 32 psi is about 2.2 bar, 1 atm is 14.6959 psi (760 mmHg), and 1 MPa is 145.038 psi (10 bar). The converter shows every unit at once, so whether you're reading a European spec in bar or a US one in psi, the figure you need is there.
Frequently Asked Questions
× 0.0689476 (÷ 14.5038). 32 psi ≈ 2.2 bar.
× 0.145038. 100 kPa = 14.5038 psi = 1 bar.
101,325 Pa = 1.01325 bar = 14.6959 psi = 760 mmHg.
Gauge is relative to atmosphere; add ~14.696 psi (1.01325 bar) for absolute.
From mercury barometers: 1 mmHg = 133.322 Pa; 760 mmHg = 1 atm.