Pressure Converter
Convert bar, psi, kPa, MPa, atm, torr and mmHg for tyres, weather, diving, HVAC and engineering.
- InstantResults update as you type
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How to use this tool
Steps for using the Unit Converter.
- Type a number into From — bars are preselected. Commas and scientific notation such as 2.5e3 are accepted.
- Pick the units to convert between; the result in pounds per square inch (or whichever unit you choose) updates as you type. Use the swap button to reverse the conversion.
- Set the decimal places, turn on Show formula to see the calculation, and copy or share the result.
- Below the converter, the table lists every pressure unit with its exact definition, and the links open dedicated pages for the most common pairs.
Example
2.2 bars to pounds per square inch
2.2 bar31.908302 psi
Formula: psi = bar × 14.50377377Common use cases
- Tyre pressures in bar, psi and kPa.
- Weather and altitude pressures in hPa (mbar) and atm.
- Hydraulics, pneumatics and diving.
Pressure unit table
| Unit | Symbol | System | Definition | In pascals |
|---|---|---|---|---|
| Pascal | Pa | SI | 1 N/m², the SI unit of pressure | 1 |
| Kilopascal | kPa | Metric | 1,000 Pa | 1,000 |
| Megapascal | MPa | Metric | 1,000,000 Pa | 1,000,000 |
| Bar | bar | Metric | Exactly 100,000 Pa | 100,000 |
| Millibar | mbar | Metric | 100 Pa = 1 hPa | 100 |
| Pound per square inch | psi | US customary | 1 lbf/in² ≈ 6,894.757 Pa | 6,894.7572931684 |
| Standard atmosphere | atm | Other | Exactly 101,325 Pa | 101,325 |
| Torr | Torr | Other | 1/760 atm ≈ 133.3224 Pa | 133.3223684211 |
| Millimeter of mercury | mmHg | Other | Exactly 133.322387415 Pa (conventional) | 133.322387415 |
Popular pressure conversions
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About pressure units
Pressure is force per area; the SI unit is the pascal (1 N/m²), which is tiny, so kilopascals and megapascals are common. The bar is exactly 100,000 Pa — close to atmospheric pressure — and the millibar equals the hectopascal used on weather maps.
The psi (pound-force per square inch) is about 6,894.76 Pa. The standard atmosphere is exactly 101,325 Pa. Torr (1/760 atm) and mmHg (exactly 133.322387415 Pa) are nearly identical but not the same; mmHg is still used for blood pressure.
Tyre and compressor gauges show gauge pressure — pressure above the surrounding atmosphere. Converting units doesn't change that: 2.2 bar gauge is 31.9 psi gauge.
Limitations
- Results are rounded for display only; the calculation keeps full precision (15 significant digits).
Frequently asked questions
How many psi are in a bar?
1 bar = 14.5038 psi.
Is mmHg the same as torr?
Almost: 1 Torr = 133.3224 Pa and 1 mmHg = 133.3224 Pa differ only in the seventh significant digit. For everyday use they're interchangeable.
Is a millibar the same as a hectopascal?
Yes, exactly: both are 100 Pa.
Are these pressure conversions exact?
Each unit is defined from its official definition (for example 1 inch = 2.54 cm exactly). Results are calculated in double precision and only rounded to the decimal places you choose when shown.