Pressure Converter
Turn any pressure into a different unit — pascal, bar, atmosphere, psi, mmHg, and more — using exact, published factors.
Pascal-based
Every unit is a fixed multiple of the pascal, so the converter pivots through pascals for one consistent rule.
Display rounding
Results are shown to six decimal places, so very large or very small conversions may round the last digit.
What is a pressure converter?
One value, any unit
A pressure converter changes a reading from one unit into another — bar to psi, psi to bar, pascal to atmosphere, mmHg to kilopascal, and back. It works by translating every value through a single shared pivot, the pascal (Pa), so any pair of units converts with one consistent rule. This tool covers the ten units used in weather, engineering, tyres, diving, and medicine: pascal, hectopascal, kilopascal, megapascal, bar, millibar, atmosphere, psi, mmHg, and inHg.
Unlike temperature, pressure units share a zero point, so converting is purely multiplicative — scale by the factor in, then by the factor out.
result = value × (Pa per from-unit) ÷ (Pa per to-unit)Because the pascal is the SI base unit, each unit has a fixed number of pascals: 1 bar is 100,000 Pa, 1 atm is exactly 101,325 Pa, 1 psi is about 6894.757 Pa. The converter turns your value into pascals first, then into the unit you want — so a single rule handles every direction.
Suppose you want to convert 1 bar into psi.
Convert to pascals
Multiply by the bar factor: 1 × 100,000 = 100,000 Pa.Convert out to psi
Divide by the psi factor: 100,000 ÷ 6894.757 = 14.5038.Read the result
1 bar converts to 14.5038 psi — roughly the pressure in a well-inflated car tyre.
Pressure conversion is a simple ratio, so the everyday anchors are easy to remember: sea-level air pressure is about 1 atm ≈ 1.013 bar ≈ 1013 hPa ≈ 14.7 psi. Weather forecasts use hectopascals, tyre gauges use bar or psi, scuba depth tables use bar, and blood-pressure cuffs use mmHg. As quick sanity checks, a typical car tyre runs 30–35 psi, which is about 2.0–2.4 bar, and every 10 metres of descent in sea water adds roughly 1 bar. If a converted number looks far off by a factor of ten or a hundred, check that the from-unit and to-unit are not swapped — the swap arrow flips them in one click.
The arithmetic is exact; the limits are about precision and unit definitions.
Precision and gauge vs absolute
The psi, mmHg, and inHg factors are the conventional NIST values; the bar and standard atmosphere are exact by definition. Results are rounded to six decimal places, so conversions with long decimal tails may lose the last digit. This tool converts absolute pressure values — it does not distinguish gauge pressure (psig, measured above the surrounding air) from absolute pressure (psia), so subtract or add one atmosphere yourself when a reading is a gauge value.