Pressure converter
Convert pressure between pascals, bars, atmospheres and psi.
Fill in the fields and the result will appear here automatically.
Converts pressure between pascals, bars, atmospheres, psi and millimetres of mercury. Four systems meet in one list: gauges and tyres use bar or psi, weather reports use hectopascals, and medicine uses millimetres of mercury.
How it works
Formula and logic
Every unit converts through the pascal using exact factors.
Example
One bar is 100,000 Pa and about 14.5 psi.
Fields and units
- Pressure — in the selected source unit
- From unit — list option
- To unit — list option
How to use
- — Enter the value.
- — Pick the source unit.
- — Pick the target unit.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- BIPM: SI Brochure, version 4.01 (2026) NIST: conversion-factor tables, Appendix B.9
- Limitation
- The result is a rounded unit conversion. Check the entered value and selected units.
FAQ
Are bar and atmosphere the same?
Almost: a bar is 100,000 Pa and an atmosphere is 101,325 Pa, about 1.3% apart.
What pressure should tyres have?
This converter does not choose a tyre pressure. Use the value and measurement conditions specified for your vehicle, then convert that stated unit into the required one.
Why does medicine use millimetres of mercury?
A historical unit from the mercury manometer: 1 mmHg is exactly 133.322387415 Pa. Standard atmosphere is 760 torr, which comes to 759.9999 conventional millimetres — the torr and the mmHg are defined slightly differently.
What is a hectopascal in weather reports?
It is 100 Pa, exactly one millibar. The two units are numerically identical.