Millimeter of Mercury (mmHg)
The conventional millimetre of mercury (mmHg) is the pressure exerted by a 1 mm column of mercury of density 13 595.1 kg/m³ under standard gravity: exactly 133.322387415 Pa.
Symbol: mmHg
Quantity: pressure, stress and differential pressure (force per unit area)
SI relation: 1 mmHg = 133.322387415 Pa (exact)
Derivation: 1 mmHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.001 m = 133.322387415 Pa
Exact: yes, by definition
Reference conditions. Conventional mercury column: ρ = 13 595.1 kg/m³ and gₙ = 9.80665 m/s² (≈ mercury at 0 °C / 32 °F).
History
Mercury manometers made mmHg the standard unit for blood pressure, and it remains so in medicine worldwide. 1 mmHg = 1.000000142 Torr.
Typical uses
- Blood pressure (e.g. 120/80 mmHg)
- Intraocular and intracranial pressure
- Laboratory manometers and barometers
Convert millimeters of mercury to other units
Open the Pressure Converter to convert any value between all units.
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)".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Millimeter of Mercury (mmHg). Retrieved October 17, 2026, from https://scientificconverters.com/units/millimeter-of-mercury/
IEEE
Scientific Converters, "Millimeter of Mercury (mmHg)," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/units/millimeter-of-mercury/