Convert Millimeters of Mercury to Millibars

Formula

mbar = mmHg × 1.33322387415

Derivation from SI units:

• 1 mmHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.001 m = 133.322387415 Pa
• 1 mbar = 10⁻³ bar = 100 Pa = 1 hPa
• 1 mmHg = 133.322387415 Pa ÷ 100 Pa per mbar = 1.33322387415 mbar

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

Worked examples

1. A reading of 80 mmHg converts to 106.6579099 mbar.
   80 mmHg × 1.333223874 = 106.6579099 mbar
2. A value of 160 mmHg is 213.3158199 mbar.
   160 mmHg × 1.333223874 = 213.3158199 mbar

Where it's used

Millimeters of Mercury are used for blood pressure (e.g. 120/80 mmHg), while millibars appear in weather maps and barometers (sea level ≈ 1013 mbar). 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, "millibar".

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