Convert mm Hg to mbar – Pressure Unit Conversion Example

Worked Pressure Unit Conversion Problem – Millimeters Mercury to Millibars

Pressure Gauge
Sometimes you can get lucky and have a pressure gauge with different units. Otherwise, you’ll need to know how to convert mm Hg to mbar.

This example problem demonstrates how to convert the pressure unit millimeters of mercury (mm Hg) to millibar (mbar).

Millimeters of mercury is a pressure measurement usually associated with barometers and common in meteorology. A glass tube is sealed at one end and the open end is submerged into a pool of liquid mercury. Differences in air pressure on the mercury cause the level of the mercury to rise and fall inside the glass tube. The differences in height are measured in millimeters, which explains the name “millimeters of mercury”.

The bar is a pressure unit defined as 100 kilopascals and is often seen in meteorology. One bar contains 1000 millibars or 1 millibar is 1/1000 bar.

The conversion factor between mm Hg and mbar is

1 mbar = 0.75218 mm Hg
1 mm Hg = 1.33322368 millibars

Example Problem: Convert mm Hg to mbar

The average air pressure at sea level is 760 mm Hg. What is this pressure in millibars?


1 mbar = 0.75218 mm Hg

Set up the conversion so the desired unit is on top. This allows the unwanted unit to be canceled out. In this case, we want mbar to be the remaining unit.

mm Hg to mbar conversion step 1
mm Hg to mbar step 2

Cancel out the mm Hg to leave the mbar unit.

mm Hg to mbar step 3

pressure in mbar = 1010 mbar


The average sea level air pressure is 1010 mbar.