Convert Millimeters of Mercury to Decibars

Formula

dbar = mmHg × 0.0133322387415

or dbar = mmHg ÷ 75.00615758457

Derivation from SI units:

• 1 mmHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.001 m = 133.322387415 Pa
• 1 dbar = 10⁻¹ bar = 10⁴ Pa
• 1 mmHg = 133.322387415 Pa ÷ 10000 Pa per dbar = 0.0133322387415 dbar

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

Worked examples

1. A reading of 80 mmHg converts to 1.066579099 dbar.
   80 mmHg × 0.01333223874 = 1.066579099 dbar
2. A value of 160 mmHg is 2.133158199 dbar.
   160 mmHg × 0.01333223874 = 2.133158199 dbar

Where it's used

Millimeters of Mercury are used for blood pressure (e.g. 120/80 mmHg), while decibars appear in oceanography: CTD instruments report sea pressure in dbar. 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", with SI prefix deci (10⁻¹).

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