Pressure Converter
Convert between pascals, kilopascals, bar, psi, atmospheres, and mmHg instantly.
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About this pressure converter
This tool converts between 6 common pressure units, from pascals up to atmospheres. Pick any two units, enter a value, and the result updates instantly — every conversion happens with simple arithmetic directly in your browser, so there's no network request, no waiting, and it keeps working even if you lose your internet connection.
Common real-world uses
Tire pressure specs (psi in the US, bar or kPa almost everywhere else), weather barometric readings, scuba diving depth gauges, hydraulic system specs, and blood pressure readings (mmHg) all use different pressure units by regional or industry convention — this tool covers translating between all of them.
Units covered
- Pascal (Pa) — the SI unit of pressure, defined as one newton of force per square meter — small enough that everyday pressures run in the thousands or millions of pascals.
- Kilopascal (kPa) — equal to 1,000 pascals, a common unit for tire pressure specs and weather barometric readings outside the US.
- Bar (bar) — defined as exactly 100,000 pascals, chosen to be close to average sea-level atmospheric pressure — widely used in Europe for tire pressure and diving.
- Pound per Square Inch (psi) — the standard pressure unit in the US for tire pressure, hydraulics, and plumbing specs.
- Standard Atmosphere (atm) — defined as exactly 101,325 pascals, representing average air pressure at sea level — used as a reference point across chemistry and engineering.
- Millimeter of Mercury (mmHg) — the traditional unit for blood pressure readings and older barometers, based on how high a column of mercury rises under a given pressure.
Frequently asked questions
What tire pressure should I use, psi or bar?
Match whatever your vehicle's door-jamb sticker or manual specifies — US vehicles and gauges are almost always in psi, while most of Europe and Asia use bar or kPa. This converter is exactly for translating a spec from one convention to the gauge you actually have.
Why is 1 atmosphere not a round number in pascals?
Standard atmosphere is defined as exactly 101,325 pascals — a historical figure chosen to represent typical air pressure at sea level, not a round metric number, which is why it looks like an odd figure when converted.
Why is blood pressure measured in mmHg instead of a metric unit?
Millimeters of mercury dates back to early mercury-column barometers and stuck as the medical convention worldwide even as most other pressure measurements moved to metric units like pascals and bar.
Does this work offline?
Yes — every conversion is a simple multiplication done in your browser, so it keeps working without an internet connection once loaded.