How many mm H2O in 1 inch mercury?
The answer is 345.31557667501.
We assume you are converting between millimeter water [4 °C] and .
You can view more details on each measurement unit:
mm H2O or
inch mercury
The SI derived unit for pressure is the pascal.
1 pascal is equal to 0.10197162129779 mm H2O, or 0.00029529980164712 inch mercury.
Note that rounding errors may occur, so always check the results.
Use this page to learn how to convert between millimeters water and inches mercury.
Type in your own numbers in the form to convert the units!
1 mm H2O to inch mercury = 0.0029 inch mercury
10 mm H2O to inch mercury = 0.02896 inch mercury
50 mm H2O to inch mercury = 0.1448 inch mercury
100 mm H2O to inch mercury = 0.28959 inch mercury
200 mm H2O to inch mercury = 0.57918 inch mercury
500 mm H2O to inch mercury = 1.44795 inch mercury
1000 mm H2O to inch mercury = 2.8959 inch mercury
You can do the reverse unit conversion from inch mercury to mm H2O, or enter any two units below:
mm H2O to nanobar
mm H2O to inch water column
mm H2O to kip/square foot
mm H2O to yoctobar
mm H2O to technical atmosphere
mm H2O to attopascal
mm H2O to foot water
mm H2O to zeptobar
mm H2O to ton/square inch
mm H2O to millitorr
Inches of mercury or inHg is a non-SI unit for pressure. It is still widely used for barometric pressure in weather reports and aviation in the United States, but is considered somewhat outdated elsewhere.
It is defined as the pressure exerted by a column of mercury of 1 inch in height at 32 °F (0 °C) at the standard acceleration of gravity.
1 inHg = 3,386.389 pascals at 0 °C.
Aircraft operating at higher altitudes (above 18,000 feet) set their barometric altimeters to a standard pressure of 29.92 inHg or 1,013.2 hPa (1 hPa = 1 mbar) regardless of the actual sea level pressure, with inches of mercury used in the U.S. and Canada. The resulting altimeter readings are known as flight levels.
Piston engine aircraft with constant-speed propellers also use inHg to measure manifold pressure, which is indicative of engine power produced.
ConvertUnits.com provides an online conversion calculator for all types of measurement units. You can find metric conversion tables for SI units, as well as English units, currency, and other data. Type in unit symbols, abbreviations, or full names for units of length, area, mass, pressure, and other types. Examples include mm, inch, 100 kg, US fluid ounce, 6'3", 10 stone 4, cubic cm, metres squared, grams, moles, feet per second, and many more!