How to use this pressure converter
- Type the pressure in the From box. The page opens with 32.
- Pick its unit in the From menu. It covers pascal, hPa or millibar, kPa, MPa, bar, kgf/cm², psi, inHg, inH₂O, atm, mmHg, torr and cmH₂O.
- Pick the unit you want in the To menu. The To box updates as you type, and typing in the To box converts the other way.
- Press Swap units to flip the menus. The panel below lists the same pressure in every unit.
How the conversion works
Every pressure is converted to pascals and then to your target unit: value × (From unit in Pa) ÷ (To unit in Pa). A standard atmosphere is exactly 101,325 Pa and a bar is exactly 100,000 Pa. A psi is one pound-force (4.4482216152605 N) on one square inch (0.00064516 m²), which is 6,894.757293168 Pa. A conventional millimeter of mercury is 133.322387415 Pa, an inch of mercury is 25.4 of those (3,386.38864 Pa), and a torr is exactly 101,325 ÷ 760 = 133.322368 Pa. A conventional inch of water is 249.08891 Pa and a centimeter of water is 98.0665 Pa. These agree with NIST SP 811, Appendix B.8. Results use 8 significant digits, with whole numbers shown in full.
Worked example: 32 psi in bar
With the default inputs the tool computes 32 × 6,894.757293168 ÷ 100,000 and shows 32 psi = 2.2063223 bar, with the reverse line 1 bar = 14.503774 psi. The panel below it gives the same pressure as 220.63223 kPa, 2.1774708 atm and 1,654.8776 mmHg.
Common tire pressures and weather readings
| Pressure | Bar | kPa |
|---|---|---|
| 30 psi | 2.0684 | 206.84 |
| 32 psi | 2.2063 | 220.63 |
| 35 psi | 2.4132 | 241.32 |
| 40 psi | 2.7579 | 275.79 |
| 1 atm (sea level) | 1.0133 | 101.33 |
Standard sea level pressure is also 1,013.25 hPa, exactly 760 torr (about 760 mmHg), 29.921256 inHg and 14.695949 psi. A blood pressure of 120 mmHg is 15.999 kPa.
Limits and edge cases
The tool changes units only. It cannot turn gauge pressure into absolute pressure, because that needs the local air pressure; at sea level add about 14.696 psi. Negative values are accepted so that vacuum readings on a gauge scale can be converted. Mercury and water columns depend on temperature and gravity, so the tool uses the conventional values (mercury at 0 °C, water at about 4 °C, standard gravity), as NIST does. Medical readings are converted only; the tool does not interpret them. You can type 1,250 with a thousands comma or 2,5 with a decimal comma, and a pasted 1.5e6 becomes plain digits. Values above 1,000,000,000,000,000,000,000,000 are refused.
Setting tires? The tire size calculator covers dimensions. For readings you want interpreted, use the blood pressure analyzer. Dive and weather work often needs the temperature converter too.
Frequently asked questions
How do I convert psi to bar?
Divide the psi by 14.503774, or multiply by 0.068947573. For example, 32 psi = 2.2063223 bar.
How many kPa is 1 psi?
One psi is 6.8947573 kPa. Multiply psi by 6.8947573 to get kPa, or multiply kPa by 0.14503774 to get psi.
Are mmHg and torr the same?
For practical purposes, yes. A torr is exactly 1/760 of a standard atmosphere, 133.32237 Pa, and a conventional mmHg is 133.32239 Pa. They differ by about 0.00001 percent.
What is the difference between a bar and an atmosphere?
A bar is exactly 100 kPa and a standard atmosphere is 101.325 kPa, so 1 atm is 1.01325 bar. A bar is about 1.3 percent smaller than an atmosphere.
How do I convert hPa to inHg?
Multiply hectopascals (millibars) by 0.029529983. Standard sea level pressure of 1,013.25 hPa is 29.921256 inHg.
Sources: NIST SP 811, Appendix B.8 and Appendix B.9, conversion factors for pressure units.