Inch of Mercury (inHg)
A unit of pressure used in aviation and meteorology based on the height of a mercury column
The Inch of Mercury (inHg) 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 Inch 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 inHg = |
|---|---|---|
| Pascal | Pa | 3386.39 Pa |
| Kilopascal | kPa | 3.38639 kPa |
| Bar | bar | 0.0338639 bar |
| Atmosphere | atm | 0.0334211 atm |
| Pound per Square Inch | psi | 0.491154 psi |
| Millimeters of Mercury | mmHg | 25.4001 mmHg |
| Megapascal | MPa | 0.00338639 MPa |
| Gigapascal | GPa | 0.00000338639 GPa |
| Kilopound per Square Inch | ksi | 0.000491154 ksi |
| Torr | torr | 25.4001 torr |
| Kilogram-force per Square Centimeter | kgf/cm² | 0.0345316 kgf/cm² |
Conversions Involving Inch of Mercury
Pascal → Inch of Mercury
Pa → inHg
Kilopascal → Inch of Mercury
kPa → inHg
Bar → Inch of Mercury
bar → inHg
Atmosphere → Inch of Mercury
atm → inHg
Pound per Square Inch → Inch of Mercury
psi → inHg
Millimeters of Mercury → Inch of Mercury
mmHg → inHg
Megapascal → Inch of Mercury
MPa → inHg
Gigapascal → Inch of Mercury
GPa → inHg
Kilopound per Square Inch → Inch of Mercury
ksi → inHg
Torr → Inch of Mercury
torr → inHg
Inch of Mercury → Pascal
inHg → Pa
Inch of Mercury → Kilopascal
inHg → kPa
Inch of Mercury → Bar
inHg → bar
Inch of Mercury → Atmosphere
inHg → atm
Inch of Mercury → Pound per Square Inch
inHg → psi
Inch of Mercury → Millimeters of Mercury
inHg → mmHg
Inch of Mercury → Megapascal
inHg → MPa
Inch of Mercury → Gigapascal
inHg → GPa
Inch of Mercury → Kilopound per Square Inch
inHg → ksi
Inch of Mercury → Torr
inHg → torr
Inch of Mercury → Kilogram-force per Square Centimeter
inHg → kgf/cm²
Kilogram-force per Square Centimeter → Inch of Mercury
kgf/cm² → inHg
Common Uses of the Inch 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 Inch of Mercury is one of several units used to express pressures across this extraordinary range.