›› Convert to millimeter water [4 °C]

inch mercury
millimeter water

›› More information from the unit converter

How many inch mercury in 1 millimeter water? The answer is 0.0028959017998228.
We assume you are converting between and millimeter water [4 °C].
You can view more details on each measurement unit:
inch mercury or millimeter water
The SI derived unit for pressure is the pascal.
1 pascal is equal to 0.00029529980164712 inch mercury, or 0.10197162129779 millimeter water.
Note that rounding errors may occur, so always check the results.
Use this page to learn how to convert between inches mercury and millimeters water.
Type in your own numbers in the form to convert the units!

›› Quick conversion chart of inch mercury to millimeter water

1 inch mercury to millimeter water = 345.31558 millimeter water

2 inch mercury to millimeter water = 690.63115 millimeter water

3 inch mercury to millimeter water = 1035.94673 millimeter water

4 inch mercury to millimeter water = 1381.26231 millimeter water

5 inch mercury to millimeter water = 1726.57788 millimeter water

6 inch mercury to millimeter water = 2071.89346 millimeter water

7 inch mercury to millimeter water = 2417.20904 millimeter water

8 inch mercury to millimeter water = 2762.52461 millimeter water

9 inch mercury to millimeter water = 3107.84019 millimeter water

10 inch mercury to millimeter water = 3453.15577 millimeter water

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You can do the reverse unit conversion from millimeter water to inch mercury, or enter any two units below:

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›› Common pressure conversions

inch mercury to dyne/square centimeter
inch mercury to foot of mercury
inch mercury to gram/square centimeter
inch mercury to meter of head
inch mercury to centihg
inch mercury to millimeter of water
inch mercury to gigabar
inch mercury to yottabar
inch mercury to femtopascal
inch mercury to kilopascal

›› Definition: Inch mercury

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widely used for barometric pressure in weather reports and aviation in the United States, but is considered somewhat outdated elsewhere.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.

›› Metric conversions and more

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!