The unit mm Hg (millimeter of mercury) is often called the torr in honor of Torricelli. The terms torr and mm Hg are used interchangeably by chemists. A related unit for pressure is the standard atmosphere (abbreviated atm):
1 standard atmosphere = 1 atm = 760 mm Hg = 760 torr
However, since pressure is defined as force per unit area,
Pressure = force/area