How many inch of mercury in 1 mmH2O? The answer is 0.0028959020848759. We assume you are converting between inch of mercury [0 °C] and millimeter of water [4 °C]. You can view more details on each measurement unit: inch of mercury or mmH2O The SI derived unit for pressure is the pascal. 1 pascal is equal to 0.00029529983071445 inch of mercury, or 0.10197162129779 mmH2O. Note that rounding errors may occur, so always check the results. Use this page to learn how to convert between inches of mercury and millimeters of water. Type in your own numbers in the form to convert the units!
1 inch of mercury to mmH2O = 345.31554 mmH2O
2 inch of mercury to mmH2O = 690.63109 mmH2O
3 inch of mercury to mmH2O = 1035.94663 mmH2O
4 inch of mercury to mmH2O = 1381.26217 mmH2O
5 inch of mercury to mmH2O = 1726.57771 mmH2O
6 inch of mercury to mmH2O = 2071.89326 mmH2O
7 inch of mercury to mmH2O = 2417.2088 mmH2O
8 inch of mercury to mmH2O = 2762.52434 mmH2O
9 inch of mercury to mmH2O = 3107.83988 mmH2O
10 inch of mercury to mmH2O = 3453.15543 mmH2O
You can do the reverse unit conversion from mmH2O to inch of mercury, or enter any two units below:
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widely used for barometric pressure in weather reports and aviation in the United States, but is considered somewhat outdated elsewhere.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.
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