Pressure Converter
Convert tyre pressure, weather pressure and lab pressure units instantly.
What this tool does
To convert pressure, multiply by the exact factor between the two units - 1 standard atmosphere is exactly 101,325 pascals, and 1 psi is about 6,894.76 pascals. This tool converts between six units at once - pascals, kilopascals, bar, atmospheres, psi and millimetres of mercury - and shows the exact factor used.
Converts pressure between six units - pascals, kilopascals, bar, atmospheres, psi and millimetres of mercury.
Covers the units that actually show up day to day: tyre pressure (psi/bar), weather pressure (mmHg/hPa-equivalent kPa) and lab/engineering pressure (Pa, atm).
How to use it
- Enter the pressure value you want to convert.
- Pick the unit you're converting from and the unit you're converting to.
- Read the result, or press Swap units to reverse it.
Why use this converter
Pressure appears as psi on tyres, bar in Europe, kPa in weather and engineering, and mmHg in medicine, with atmosphere as a reference. Mixing them up is both common and costly for tyres and equipment.
Why we built it
We built the pressure converter around the units people actually meet - tire, weather and lab pressure - in one tool. For tire pressure pairs use the psi to bar converter and check gas behaviour with the ideal gas law calculator.
Related tools worth a look: the Temperature Converter.
Handy alongside this: the Dew Point Calculator.
Who this tool is for
- Drivers inflating tires
- Divers, brewers and engineers
- Weather watchers
When to use it
- Setting tyre pressures from a manual in another unit.
- Reading weather barometer values.
- Engineering, plumbing and scuba or compressor settings.
- Science and medical pressure values.
Where each unit is actually used
Different industries settled on different defaults.
Car and bicycle tyres are usually pressured in psi in the US and increasingly in bar or kPa elsewhere - a typical car tyre runs around 30-35 psi, or about 2.1-2.4 bar. Weather forecasts and barometric readings traditionally use millimetres of mercury or, more commonly today, hectopascals (numerically identical to kilopascals × 10, i.e. 1 hPa = 0.1 kPa) - standard sea-level atmospheric pressure is about 1,013 hPa or 101.325 kPa. Laboratory and scientific work often uses the pascal directly, or atmospheres for a round, easy-to-reason-about reference point.
One standard atmosphere, several definitions of pressure
The standard atmosphere (atm) is defined as exactly 101,325 pascals - a fixed reference figure for average sea-level air pressure, not a measurement that varies. Everything else in this tool converts through that same pascal base, so a psi-to-bar conversion and a psi-to-atm conversion both use the same underlying pascal figure, just expressed in a different unit at the end.
What you give it, and what you get back
| Item | Details |
|---|---|
| Value | A pressure in the "from" unit. |
| From and To | Pa, kPa, bar, atm, psi or mmHg. |
| Output | The converted pressure and the exact factor. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Tyre pressure advice expected | This converts numbers only. | Always follow the manufacturer's recommended pressure. |
| Gauge vs absolute | Gauge pressure ignores atmospheric pressure. | The tool converts the number as given. |
| mmHg looks small | One mmHg is about 133 Pa. | This is normal. |
Assumptions and limitations
- This converts a pressure value between units. It does not calculate tyre pressure recommendations for a specific vehicle - always follow the vehicle manufacturer's stated figure.
- Real atmospheric pressure varies with weather and altitude; 101,325 Pa is a fixed reference standard, not the pressure at any given moment or location.
- Very small or very large results are shown with practical rounding for readability; the internal calculation is exact.
Frequently asked questions
How many psi are in a bar?
About 14.5 psi in 1 bar, since 1 bar is exactly 100,000 pascals and 1 psi is about 6,894.76 pascals. This tool gives the precise figure for any value, not just round numbers.
What is 1 atmosphere in psi?
About 14.696 psi. One standard atmosphere is defined as exactly 101,325 pascals, which converts to roughly 14.696 psi using the exact pascal-to-psi factor.
How do I convert kPa to psi?
Divide the kPa figure by about 6.895, or multiply by roughly 0.145. This tool does the exact calculation instantly for any value.
What tyre pressure is 32 psi in bar?
About 2.2 bar. 32 psi is a very common recommended car tyre pressure in the US, and 2.2 bar is the equivalent figure you'd see quoted in a country using bar or kPa instead.
What is standard atmospheric pressure in different units?
Exactly 101,325 Pa (101.325 kPa), exactly 1 atm by definition, exactly 1013.25 hPa, and about 14.696 psi or 760 mmHg. All of these describe the same fixed reference standard for average sea-level pressure.
Are these pressure conversion factors exact?
Yes for the defined units - the atmosphere (101,325 Pa) and the bar (100,000 Pa) are exact by definition. The psi and mmHg factors are exact to the precision shown, based on the standard pound and the standard gravity/mercury-density figures used to define them.
Sources and accuracy
Exact internationally defined constants: 1 standard atmosphere = 101,325 Pa exactly; 1 bar = 100,000 Pa exactly.
Figures last checked against the source on . Standards and rates can change — if you are relying on this for something that matters, confirm against the source above. Think a figure is wrong or out of date? Send a correction.