Inch of Mercury (inHg)

The conventional inch of mercury (inHg) is the pressure of a 1 inch column of mercury of density 13 595.1 kg/m³ under standard gravity: 3386.388640341 Pa.

Symbol: inHg

Quantity: pressure, stress and differential pressure (force per unit area)

SI relation: 1 inHg = 3386.388640341 Pa (exact)

Derivation: 1 inHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.0254 m = 3386.388640341 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).

Typical uses

Aircraft altimeter settings (standard 29.92 inHg)
US weather reports of barometric pressure
Vacuum gauges on engines and HVAC recovery equipment

Convert inches of mercury to other units

1 inHg in other pressure units
Conversion	1 inHg equals	Reverse
inch of mercury to pascal	3386.38864 Pa	pascal to inch of mercury
inch of mercury to kilopascal	3.38638864 kPa	kilopascal to inch of mercury
inch of mercury to psi	0.4911541475 psi	psi to inch of mercury
inch of mercury to bar	0.0338638864 bar	bar to inch of mercury
inch of mercury to millimeter of mercury	25.4 mmHg	millimeter of mercury to inch of mercury
inch of mercury to inch of water	13.5951 inH₂O	inch of water to inch of mercury
inch of mercury to atmosphere	0.03342105739 atm	atmosphere to inch of mercury
inch of mercury to megapascal	0.00338638864 MPa	megapascal to inch of mercury
inch of mercury to millibar	33.8638864 mbar	millibar to inch of mercury
inch of mercury to torr	25.40000362 Torr	torr to inch of mercury
inch of mercury to millimeter of water	345.31554 mmH₂O	millimeter of water to inch of mercury
inch of mercury to centimeter of water	34.531554 cmH₂O	centimeter of water to inch of mercury
inch of mercury to decibar	0.338638864 dbar	decibar to inch of mercury
inch of mercury to inch of water (60 °F)	13.60869892 inH₂O (60 °F)	inch of water (60 °F) to inch of mercury
inch of mercury to barye	33863.8864 Ba	barye to inch of mercury

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, "inch of mercury, conventional (inHg)".

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

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APA

Scientific Converters. (2026, October 15). Inch of Mercury (inHg). Retrieved October 18, 2026, from https://scientificconverters.com/units/inch-of-mercury/

IEEE

Scientific Converters, "Inch of Mercury (inHg)," scientificconverters.com. Accessed: Oct. 18, 2026. [Online]. Available: https://scientificconverters.com/units/inch-of-mercury/