Pressure Converter

Worked example

1 atm = 101,325 Pa exactly and 1 bar = 100 kPa. 1 psi ≈ 6.894757293 kPa, and 1 atm ≈ 14.69594878 psi. 760 torr = 1 atm exactly.

How it works

Every unit converts through the pascal using exact defined factors: the standard atmosphere is exactly 101,325 Pa, the bar is exactly 100,000 Pa, the millibar and hectopascal are both 100 Pa, and psi is one pound-force per square inch. The torr is defined as 1/760 of an atmosphere, so 760 torr is exactly 1 atm. A millimetre of mercury (mmHg) is defined slightly differently, from the density of mercury and standard gravity (133.322387415 Pa), so it is very close to the torr but not identical: 760 mmHg ≈ 1.000000142 atm. Inches of mercury and centimetres of water are not included.

Signed values are accepted, because a negative pressure can be a gauge or differential reading, meaning below the surrounding pressure. It does not mean a negative absolute pressure. This tool converts units only and gives no interpretation of any reading.

A result written as a plain number is exact. A result starting with “≈” has been rounded to 10 significant figures, because its exact decimal never ends or is too long to read comfortably. When an exact value is long, its full digits are shown underneath. The calculation itself is never rounded: only the display is.