Convert Millimeters of Mercury to Bar

Formula

bar = mmHg × 0.00133322387415

or bar = mmHg ÷ 750.0615758457

Derivation from SI units:

• 1 mmHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.001 m = 133.322387415 Pa
• 1 bar = 10⁵ Pa (exact, by definition)
• 1 mmHg = 133.322387415 Pa ÷ 100000 Pa per bar = 0.00133322387415 bar

Both units are defined exactly, so the factor is exact. Millimeter of Mercury definition: millimeter of mercury; Bar definition: bar.

Worked examples

1. A reading of 80 mmHg converts to 0.1066579099 bar.
   80 mmHg × 0.001333223874 = 0.1066579099 bar
2. A value of 160 mmHg is 0.2133158199 bar.
   160 mmHg × 0.001333223874 = 0.2133158199 bar

Where it's used

Millimeters of Mercury are used for blood pressure (e.g. 120/80 mmHg), while bar appear in compressed air and pneumatics (6–8 bar). Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.

Millimeter of Mercury to other pressure units

Frequently asked questions

Sources

• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "millimeter of mercury, conventional (mmHg)".
• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "bar".

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.