How many mm H2O in 1 millimeter mercury?
The answer is 13.5951.

We assume you are converting between **millimeter water [4 °C]** and .

You can view more details on each measurement unit:

mm H2O or
millimeter mercury

The SI derived unit for **pressure** is the pascal.

1 pascal is equal to 0.10197162129779 mm H2O, or 0.0075006157584566 millimeter mercury.

Note that rounding errors may occur, so always check the results.

Use this page to learn how to convert between millimeters water and millimeters mercury.

Type in your own numbers in the form to convert the units!

1 mm H2O to millimeter mercury = 0.07356 millimeter mercury

10 mm H2O to millimeter mercury = 0.73556 millimeter mercury

20 mm H2O to millimeter mercury = 1.47112 millimeter mercury

30 mm H2O to millimeter mercury = 2.20668 millimeter mercury

40 mm H2O to millimeter mercury = 2.94224 millimeter mercury

50 mm H2O to millimeter mercury = 3.6778 millimeter mercury

100 mm H2O to millimeter mercury = 7.35559 millimeter mercury

200 mm H2O to millimeter mercury = 14.71118 millimeter mercury

You can do the reverse unit conversion from millimeter mercury to mm H2O, or enter any two units below:

mm H2O to zeptopascal

mm H2O to millitorr

mm H2O to decitorr

mm H2O to foot water

mm H2O to pascal

mm H2O to kip/square inch

mm H2O to femtopascal

mm H2O to picobar

mm H2O to meter of head

mm H2O to centitorr

The millimeter of mercury by definition is 133.322387415 Pa (13.5951 g/cm3 × 9.80665 m/s2 × 1 mm), which is approximated with known accuracies of density of mercury and standard gravity.

The torr is defined as 1/760 of one standard atmosphere, while the atmosphere is defined as 101325 pascals. Therefore, 1 Torr is equal to

101325/760 Pa. The decimal form of this fraction is approximately 133.322368421.

The relationship between the torr and the millimeter of mercury is:

1 Torr = 0.999999857533699 mmHg

1 mmHg = 1.000000142466321 Torr

The difference between one millimeter of mercury and one torr, as well as between one atmosphere (101.325 kPa) and 760 mmHg (101.3250144354 kPa), is less than one part in seven million (or less than 0.000015%). This small difference is negligible for most applications outside metrology.

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