Standard Atmospheres to Torr (atm to Torr)
1 standard atmosphere equals 760 torr exactly.
How to convert standard atmospheres to torr
To convert standard atmospheres to torr, multiply the number of standard atmospheres by 760. This factor is exact. To go the other way, multiply torr by 0.001315789474 (rounded).
torr = standard atmospheres × 760
Example: 10 standard atmospheres = 7,600 torr.
About these units
Standard Atmosphere (atm)
Exactly 101,325 pascals, the average pressure of the atmosphere at sea level.
A column of mercury about 76 cm tall was Torricelli's measure of the air, and the standard atmosphere began as exactly that: the pressure of 760 mm of mercury at 0 degrees Celsius under standard gravity. It was used as a reference for physical and chemical properties, and the Celsius scale set 100 degrees as the boiling point of water at that pressure.
In 1954 the 10th CGPM confirmed the standard atmosphere as exactly 1,013,250 dynes per square centimeter, which is 101,325 pascals, a definition that no longer depends on the properties of any substance.
In practice one atmosphere is about 1.01325 bar, 760 mmHg, 14.696 psi or 29.92 inHg, and roughly the pressure of 10.33 meters of water. Chemistry splits on it: until 1982 standard temperature and pressure used 1 atm, but that year IUPAC recommended a standard pressure of exactly 100 kPa instead.
1 standard atmosphere = 101,325 pascals (exactly).
Sources: Wikipedia: Standard atmosphere (unit); Wikipedia: Atmospheric pressure; Wikipedia: Evangelista Torricelli
Torr (Torr)
Exactly 1/760 of a standard atmosphere (about 133.322 Pa), named after Evangelista Torricelli. Used for vacuum measurement.
In 1643 Evangelista Torricelli filled a meter-long tube, sealed at one end, with mercury and stood it in a basin of mercury. The column fell to about 76 cm and left a Torricellian vacuum above it, the first recorded creation of a permanent vacuum. In a letter dated 11 June 1644 he described living at the bottom of a sea of air, an idea that also explained why suction pumps could raise water only about 10 meters.
The torr honors him. It was originally meant to equal one millimeter of mercury at 0 degrees Celsius, but the weight of a mercury column varies with gravity, which changes with elevation and latitude. In 1954 the 10th CGPM defined the standard atmosphere as 101,325 Pa, and the torr was then fixed as exactly one 760th of that, about 133.32 Pa.
Today the torr is mostly met in high-vacuum physics and engineering. It differs from the millimeter of mercury by less than one part in seven million, so the two are interchangeable except in the most exacting work.
1 torr = 133.3223684 pascals (approximately).
Sources: Wikipedia: Torr; Wikipedia: Evangelista Torricelli; Wikipedia: Standard atmosphere (unit)
Related conversions
- Torr to standard atmospheres (reverse)
- Standard atmospheres to pascals
- Standard atmospheres to kilopascals
- Standard atmospheres to bars
- Standard atmospheres to PSI
- Standard atmospheres to hectopascals
- Standard atmospheres to megapascals
- Standard atmospheres to millibars
- Standard atmospheres to millimeters of mercury
- Standard atmospheres to inches of mercury
- Standard atmospheres to gigapascals
- Standard atmospheres to kilopounds per square inch
- Standard atmospheres to millimeters of water
- Pascals to torr
- Kilopascals to torr
- Bars to torr
- PSI to torr
- Hectopascals to torr
- Megapascals to torr
- Millibars to torr
- Millimeters of mercury to torr
- Inches of mercury to torr
See all pressure units.