Pressure Converter: Bar, psi, Pa, atm, mmHg

This tool converts a pressure between the SI unit pascal (Pa) and its multiples, bar and millibar, psi, the standard and technical atmosphere, the millimetre of mercury (mmHg) and the torr, and lists the value in all common units.

Formula: result = value × (pascals per source unit) ÷ (pascals per target unit)

The factors are definitions (NIST SP 811):

• 1 bar = 100,000 Pa; 1 mbar = 1 hPa = 100 Pa
• 1 atm = 101,325 Pa (exact); 1 torr = 101,325/760 Pa ≈ 133.322368 Pa
• 1 psi = 1 lbf/in² = 4.4482216152605 N ÷ 0.00064516 m² ≈ 6,894.757293168 Pa
• 1 kgf/cm² (technical atmosphere) = 98,066.5 Pa
• 1 mmHg (conventional) = 133.322387415 Pa

Example: a tyre pressure of 32 psi = 32 × 6,894.757293 ÷ 100,000 ≈ 2.20632233 bar. 1 atm ≈ 14.69594878 psi ≈ 1.01325 bar. A blood pressure of 120 mmHg is ≈ 15.99868649 kPa, and 1013.25 mbar is exactly 760 torr.

How to read the result The "Result" field is the value in your chosen target unit (8 decimals); the list below gives the same pressure in every unit with 6 decimals. The conversion factor shows how many target units one source unit equals. Because of rounding you may see differences in the last digit for very small values; also take care not to mix up gauge and absolute pressure.

mmHg and torr are very close but not equal: 760 mmHg = 1.00000014 atm, while 760 torr is exactly 1 atm. Blood pressure is given in mmHg, weather in hPa (mbar), tyre pressure in bar or psi.