Millimetres of Mercury (mmHg)

Millimeters of Mercury (mmHg) at a temperature of 0°C is a small metric pressure unit which is derived from the hydrostatic pressure generated by a 1 mm tall column of mercury liquid. 1 millimeter of mercury equals 133.322… pascals.

The mmHg pressure unit is mostly used in the medical industry particularly for measuring blood pressure where traditionally a liquid manometer was used as part of blood pressure testing equipment. Electronic means of measuring blood pressure are now more common but the units continue to be used by the medical profession.

The pressure that is generated by a fixed height of mercury which will vary depending on the ambient temperature and local gravity, therefore it is not an absolute pressure conversion and the preferred reference values of temperature and density can vary from country to country.