Torr to Inches Of Mercury (Torr to inHg)
1 torr equals 0.03937007313 inches of mercury (rounded).
How to convert torr to inches of mercury
To convert torr to inches of mercury, multiply the number of torr by 0.03937007313. The factor is rounded to 10 significant digits. To go the other way, multiply inches of mercury by 25.40000362 (rounded).
inches of mercury = torr × 0.03937007313
Example: 10 torr = 0.3937007313 inches of mercury.
About these units
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)
Inch Of Mercury (inHg)
About 3,386.39 pascals. US weather reports and aircraft altimeters quote barometric pressure in inches of mercury.
Barometers in the United States still speak in inches. The inch of mercury is the pressure exerted by a 1-inch (25.4 mm) column of mercury under standard gravity, which is a conventional value of about 3,386.389 pascals. Because mercury's density depends on temperature, older literature that used a 60 degrees Fahrenheit basis gives about 3,376.85 pascals instead.
Its modern home is weather and flying. US weather reports quote barometric pressure in inHg, and North America and Japan give altimeter settings in it. Aircraft at higher altitudes set their altimeters to a standard 29.92 inHg, which is where flight levels come from, and that number equals one standard atmosphere.
Mechanics know it from vacuum and boost gauges. Technicians describe refrigerant-system vacuum in inHg, automotive cooling system fill tools typically hold 22 to 27 inHg of vacuum, and railways once used it for vacuum brakes.
1 inch of mercury = 3,386.38864 pascals (approximately).
Sources: Wikipedia: Inch of mercury; Wikipedia: Standard atmosphere (unit); Wikipedia: Atmospheric pressure
Related conversions
- Inches of mercury to torr (reverse)
- Torr to pascals
- Torr to kilopascals
- Torr to bars
- Torr to standard atmospheres
- Torr to PSI
- Torr to hectopascals
- Torr to megapascals
- Torr to millibars
- Torr to millimeters of mercury
- Pascals to inches of mercury
- Kilopascals to inches of mercury
- Bars to inches of mercury
- Standard atmospheres to inches of mercury
- PSI to inches of mercury
- Hectopascals to inches of mercury
- Megapascals to inches of mercury
- Millibars to inches of mercury
- Millimeters of mercury to inches of mercury
See all pressure units.