Millimeters of Mercury (mmHg)
A unit of pressure based on the height of a mercury column, used in medicine
The Millimeters of Mercury (mmHg) is a unit of pressure with a history connected to the study of fluids, gases, and atmospheric phenomena. Evangelista Torricelli's invention of the barometer in 1643 was a landmark in pressure measurement, and subsequent work by Blaise Pascal established the mathematical foundations. The pascal — the SI unit — was named in Pascal's honor when the SI system was formalized. The Millimeters of Mercury reflects either the SI tradition or the practical conventions of specific industries that standardized their measurements independently.
Accurate pressure measurement is critical in engineering, science, commerce, and everyday life. Using the correct unit and applying conversions precisely prevents errors that can be costly or dangerous in professional applications.
Conversion Table
| Unit | Symbol | 1 mmHg = |
|---|---|---|
| Pascal | Pa | 133.322 Pa |
| Kilopascal | kPa | 0.133322 kPa |
| Bar | bar | 0.00133322 bar |
| Atmosphere | atm | 0.00131579 atm |
| Pound per Square Inch | psi | 0.0193367 psi |
| Megapascal | MPa | 0.000133322 MPa |
| Gigapascal | GPa | 1.333220e-7 GPa |
| Kilopound per Square Inch | ksi | 0.0000193367 ksi |
| Torr | torr | 1 torr |
| Inch of Mercury | inHg | 0.0393699 inHg |
| Kilogram-force per Square Centimeter | kgf/cm² | 0.00135951 kgf/cm² |
Conversions Involving Millimeters of Mercury
Pascal → Millimeters of Mercury
Pa → mmHg
Kilopascal → Millimeters of Mercury
kPa → mmHg
Bar → Millimeters of Mercury
bar → mmHg
Atmosphere → Millimeters of Mercury
atm → mmHg
Pound per Square Inch → Millimeters of Mercury
psi → mmHg
Millimeters of Mercury → Pascal
mmHg → Pa
Millimeters of Mercury → Kilopascal
mmHg → kPa
Millimeters of Mercury → Bar
mmHg → bar
Millimeters of Mercury → Atmosphere
mmHg → atm
Millimeters of Mercury → Pound per Square Inch
mmHg → psi
Millimeters of Mercury → Megapascal
mmHg → MPa
Millimeters of Mercury → Gigapascal
mmHg → GPa
Millimeters of Mercury → Kilopound per Square Inch
mmHg → ksi
Millimeters of Mercury → Torr
mmHg → torr
Millimeters of Mercury → Inch of Mercury
mmHg → inHg
Millimeters of Mercury → Kilogram-force per Square Centimeter
mmHg → kgf/cm²
Megapascal → Millimeters of Mercury
MPa → mmHg
Gigapascal → Millimeters of Mercury
GPa → mmHg
Kilopound per Square Inch → Millimeters of Mercury
ksi → mmHg
Torr → Millimeters of Mercury
torr → mmHg
Inch of Mercury → Millimeters of Mercury
inHg → mmHg
Kilogram-force per Square Centimeter → Millimeters of Mercury
kgf/cm² → mmHg
Common Uses of the Millimeters of Mercury
- •Automotive — inflating tires to manufacturer-specified pressures
- •Weather reporting — tracking barometric pressure for forecasting
- •Hydraulic systems — designing and operating fluid power equipment
- •Scuba diving — calculating safe dive depths based on partial pressures
- •Medical — measuring blood pressure and calibrating medical equipment
Did You Know?
The deepest point in the ocean — the Challenger Deep in the Mariana Trench — has a water pressure of approximately 110 MPa, or about 1,086 times standard atmospheric pressure. The Millimeters of Mercury is one of several units used to express pressures across this extraordinary range.