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Pressure Converter
PSI, bar, kPa, atmospheres and mmHg.
Pressure Converter tool
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Result
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To twelve digits
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Conversion factor
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The other way
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In scientific notation
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About the Pressure Converter
Pressure Converter covers the units pressure is quoted in across tyres, weather, diving, medicine and engineering, which is an unusually fragmented set. PSI on a tyre gauge, bar on a European one, millibar in a weather forecast, kilopascals in an engineering spec and millimetres of mercury in a blood pressure reading.
The two to know are that one bar is 14.504 psi and one atmosphere is 1.01325 bar. Bar and atmosphere are close but not equal: bar is defined as exactly 100,000 pascals for convenience, while a standard atmosphere is 101,325 pascals, which is the average pressure at sea level. They differ by about 1.3 per cent.
Tyre pressures are the commonest practical use and the one where gauge versus absolute matters. A tyre gauge reads gauge pressure, which is pressure above the surrounding air, so a tyre at 32 psi holds about 46.7 psi absolute. All conversions here are of the number you give, whichever it is.
The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.
Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.
Looking for something this does not cover? FreeToolsZone.org is more free browser-based tools, organised by job, and it is worth a look if pressure converter is only part of what you are working on.
How to use the Pressure Converter
- Choose from and toThe fields below change to match what you pick, so only the figures that matter to your case are asked for.
- Enter valueDecimals are fine, and thousands separators are accepted and ignored.
- Read the result, to twelve digits and conversion factorThe figures update as you type. The Calculate button is there if you would rather press something, but nothing waits for it.
- Copy or check the resultCopy the summary with the copy button, or open the table to check it row by row.
Features
- Shows result, to twelve digits, conversion factor, the other way and in scientific notation together, so you are not running it twice
- A results table you can read across
- Updates as you type, with no button to press and no page reload
- Copy the result in one click
- Free, no sign-up, and it runs entirely in your browser
Who uses this tool
The pressure converter is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:
- Converting a tyre pressure from psi to bar
- Reading a weather pressure in millibar or inches of mercury
- Converting an engineering spec from kPa to psi
- Comparing a reading in mmHg with one in kPa
Frequently asked questions
How many psi in a bar?
About 14.504. One bar is exactly 100,000 pascals, and one psi is 6,894.757 pascals.
Is a bar the same as an atmosphere?
Nearly. A bar is exactly 100 kPa; a standard atmosphere is 101.325 kPa. They differ by about 1.3 per cent.
Does this handle gauge versus absolute pressure?
It converts whatever number you enter. A tyre gauge reads gauge pressure, so add one atmosphere to get absolute.
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Checked and rebuilt on 2026-10-14. The method this calculator uses is described in the section above, and corrections go through the contact page.