Convert millimeters of mercury to atmospheres

Explanation

From this page you can convert millimeters of mercury to atmospheres (or mmHg to atm) simply, by using the application above.

In case you are wondering, to convert from millimeters of mercury to atmospheres you need to multiply by 0.001316. This factor is calculated using the respective definitions of the two units you can find below.

Formula

1 mmHg≈0.001316 atm

millimeters of mercurymmHg

dimension	pressure
symbol	mmHg

The conventional millimeter of mercury (mmHg) is a unit of pressure.

Definition of the millimeter of mercury

The conventional millimeter of mercury is defined using a value for the density of mercury of 13595.1 kg/m³ and the standard gravity.

Value in terms of the SI

One millimeter of mercury is 133.3224 pascals. This is an approximation.

NIST Guide to the SI, Appendix B.9

History

The most simple barometer is made of a vertical glass tube from which all air as been removed, with a sealed top and an open base submerged into mercury. The atmospheric pressure then pushes the mercury up the tube until it equalize with the pressure at the base of the column of mercury.

The pressure is then expressed as the height of the column of mercury in millimeters.

The measure is dependent on the temperature and local gravity. To ease conversion between units, the millimeter of mercury has been defined with these parameters respectively fixed to approximately 0 °C and exactly 9.80665 m/s².

atmospheresatm

dimension	pressure
symbol	atm

The standard atmosphere (atm) is a unit of pressure.

It is approximately equal to the atmospheric pressure on Earth at sea level.

Definition of the atmosphere

One standard atmosphere is equal to 101325 Pa.

10^th CGPM (1954) p. 80

History

The standard atmosphere is used during the 9^th CGPM in the definition of the international temperature scale with the value of 1013250 dynes per square centimetre. That definition is reiterated during the 10^th CGPM with the mention "for all use" and the equivalence of 101325 newtons per square meter is added (and as you all know, 1 pascal is equivalent to 1 newton per square meter).

Equivalences

One standard atmosphere is equivalent to:

Some Facts

For every 10 meters you go down under water, the pressure increases by one atm.
Venus's surface atmospheric pressure is more than 90 atm.
The atmospheric pressure at the top of Mount Everest is approximately 0.33 atm.

millimeter of mercury	mmHg	1
centimeter of mercury	cmHg	10
centimeter of mercury at 0 °C	-