Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A torr is a unit of pressure defined as 1/760 of an atmosphere. It is named after Evangelista Torricelli, an Italian physicist who invented the barometer.
5 Must Know Facts For Your Next Test
1 torr is exactly equal to 133.322 pascals (Pa).
The standard atmospheric pressure at sea level is approximately 760 torr.
Torr and millimeters of mercury (mmHg) are often used interchangeably in practice.
Converting between atmospheres and torr: 1 atm = 760 torr.
The use of the torr is common in fields such as meteorology, aviation, and medicine when measuring gas pressures.
Review Questions
Related terms
Atmosphere (atm): A unit of pressure defined as being precisely equal to the mean atmospheric pressure at sea level on Earth; it equals to approximately 101.325 kPa.
Pascal (Pa): The SI unit of pressure, equivalent to one newton per square meter (N/m²).
Millimeter of Mercury (mmHg): A unit of pressure where one mmHg is defined as the amount of force exerted by a column of mercury one millimeter high; it closely approximates one torr.