Pressure Converter
Convert pressure between the metric units (pascal, kilopascal, bar, millibar) and the imperial ones (psi, inches of mercury), plus the atmosphere and the millimetre of mercury used in weather reports and blood pressure. A tyre gauge printed in psi and a car door sticker printed in bar describe the same thing, and this converts one to the other.
Converters
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This tool runs entirely in your browser. Your data is never uploaded to a server.
How it works
How pressure units relate
pressure = force ÷ area · 1 Pa = 1 N/m² · 1 bar = 100,000 Pa
Every unit here is a fixed multiple of the pascal, the SI unit of force per unit area. The bar was chosen to sit close to atmospheric pressure, psi comes from pounds-force per square inch, and mmHg comes from the height of a mercury column the pressure can support.
- 1 standard atmosphere is exactly 101,325 Pa — 14.6959 psi, 1.01325 bar, or 760 Torr.
- The Torr is defined as exactly 1/760 atm, while the millimetre of mercury listed here comes from the density of mercury. They differ by about one part in seven million, which no gauge can resolve.
- Weather reports use hectopascals (hPa) and millibars interchangeably — they are the same size, 100 Pa.
- Gauge pressure measures above the surrounding air; absolute pressure counts from vacuum. Converting units never turns one into the other.
For reference
Pressures you might be converting
| Where | psi | bar | kPa |
|---|---|---|---|
| Car tyre, typical | 32 | 2.21 | 220.6 |
| Road bike tyre | 100 | 6.89 | 689.5 |
| Sea-level atmosphere | 14.70 | 1.013 | 101.3 |
| Household water supply | 50 | 3.45 | 344.7 |
| Espresso extraction | 130.5 | 9.00 | 900.0 |
| Blood pressure, 120 mmHg | 2.32 | 0.160 | 16.0 |
Tyre figures are gauge pressure. Always use the pressure on the vehicle's door sticker, not the maximum moulded into the tyre wall.
How to use
4 clear steps.
Enter the pressure value from your gauge, sticker, or reading.
Select the unit it is written in (e.g. psi).
Select the unit you need (e.g. bar) and read the result.
Check the full table to see the same pressure in every unit at once.
Good to know
Frequently asked questions
- How many psi is 1 bar?
- 1 bar is 14.5038 psi, and 1 psi is 0.0689 bar. Car tyre pressures are often given as 2.2 bar in Europe and 32 psi in the US, which are nearly the same pressure.
- Is tyre pressure absolute or gauge pressure?
- Tyre gauges read gauge pressure — the amount above the surrounding air. Absolute pressure adds the roughly 14.7 psi (1 atm) of atmosphere on top. This converter changes units and does not add or remove that offset.
- Why does my blood pressure use mmHg?
- Medicine kept the millimetre of mercury from the original mercury-column manometers. A 120/80 reading is 16.0/10.7 kPa, but no clinical guideline is written that way, so mmHg stayed.