Pressure Converter
Convert between pascal, bar, PSI, atm, torr, mmHg, and more.
From
To
Result
101325
Pascal (Pa)
Common conversions
| Conversion | Result |
|---|---|
| 1 atm → Pa | 101325 |
| 1 bar → psi | 14.50376808 |
| 1 psi → kPa | 6.89476 |
| 1 atm → mmHg | 760.00210018 |
| 1 kPa → mbar | 10 |
| 1 bar → atm | 0.98692327 |
Pressure units and when they are used
The pascal (Pa) is the SI unit of pressure, equal to one newton per square metre. It is very small, so kilopascals (kPa) and bars are common in everyday use — weather maps often show atmospheric pressure in millibars (mbar). In the US, pounds per square inch (PSI) is the standard for tyres, pipelines, and gas cylinders. Blood pressure is still quoted in mmHg (millimetres of mercury) in medicine, while the atmosphere (atm, 101 325 Pa) serves as a convenient reference for gas calculations. The torr is effectively equal to 1 mmHg and is used in vacuum engineering. All conversions run entirely in your browser.
Built and maintained by Meet Shah · Last updated
What this tool is used for
- Converting a tyre pressure between PSI and bar for a metric gauge.
- Reading a datasheet's pressure rating against a requirement in other units.
- Converting a blood-pressure figure in mmHg into pascals for a calculation.
- Comparing two specifications quoted in different pressure units.
- Converting an atmospheric reading for a weather calculation.
Frequently Asked Questions
- What is a pascal?
- One newton per square metre — the SI unit, and a very small one. Atmospheric pressure is about 101,325 Pa, which is why weather reports use hectopascals or millibars instead: 1013 hPa is the same number in a readable size, and 1 hPa equals 1 mbar exactly.
- What is the difference between gauge and absolute pressure?
- Gauge pressure is measured relative to the surrounding atmosphere; absolute includes it. A tyre reading 32 psi gauge is about 46.7 psi absolute. Units are often written psig and psia to disambiguate, and confusing them is a 14.7 psi error at sea level.
- Why is one atmosphere 101,325 Pa exactly?
- Because it is defined that way rather than measured — the standard atmosphere was fixed by convention in 1954. Actual sea-level pressure varies by several percent with weather, so 1 atm is a reference point, not a description of the air outside.
- Are torr and mmHg the same?
- Almost, and the tool treats them as equal at 133.322 Pa. Strictly, a torr is defined as exactly 1/760 of a standard atmosphere while a millimetre of mercury depends on mercury's density and local gravity — they differ by about one part in seven million, which no instrument here resolves.
- Why does medicine still use mmHg?
- Historical continuity with the mercury sphygmomanometer, and the fact that every clinical threshold in the literature is expressed in it. A blood pressure of 120/80 mmHg is 16.0/10.7 kPa, which is correct, unfamiliar, and would invalidate a century of reference ranges.
Common errors and gotchas
- Confusing gauge with absolute pressure, which differ by one atmosphere and are both quoted as PSI or bar.
- Assuming a bar is exactly one atmosphere, when it is close but not equal.
- Mixing up torr and mmHg, which are nearly identical and not quite the same.
- Converting a pressure difference as if it were an absolute pressure.
- Reading a burst rating as a working rating, which is a specification difference rather than a conversion.
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