1
atm
101,324.72
Pa
1
atm
101,324.72
Pa
The Torr to Atmospheres Converter converts pressure from torr to standard atmospheres (atm). The conversion is elegantly simple: 1 atm = 760 torr (exactly), so torr ÷ 760 = atm. The torr is named after Evangelista Torricelli, the Italian physicist who invented the mercury barometer in 1643.
The torr is virtually identical to the millimeter of mercury (mmHg) and is defined as exactly 1/760 of a standard atmosphere. This definition means that standard atmospheric pressure — the weight of Earth's atmosphere at sea level — corresponds to exactly 760 torr, which also equals the height of mercury supported in a barometer under standard conditions.
Torr is the standard unit in vacuum science and technology. Vacuum systems are classified by their torr ranges: rough vacuum (760–1 torr), medium vacuum (1–10³ torr), high vacuum (10³–10&sup9; torr), and ultra-high vacuum (below 10&sup9; torr). Semiconductor fabrication, particle accelerators, and space simulation chambers all specify pressures in torr. Converting these to atmospheres helps conceptualize how far below atmospheric the vacuum level is.
In medicine, blood pressure is measured in mmHg (essentially torr). Normal blood pressure of 120/80 mmHg equals approximately 0.158/0.105 atm. Understanding this relationship helps medical professionals and patients appreciate the physiological pressures involved. Our converter also provides Pascal equivalents for those working with SI units.
The formula: atm = torr ÷ 760. This is exact by definition — 1 standard atmosphere is defined as exactly 760 torr. For Pascals: Pa = torr × 133.322 (since 1 torr = 101,325/760 ≈ 133.322 Pa).
Key values: 760 torr = 1 atm (exact), 1 torr ≈ 0.001316 atm, 380 torr = 0.5 atm, 1520 torr = 2 atm. Blood pressure 120 mmHg ≈ 0.158 atm. A good laboratory vacuum pump reaches about 10⁻³ torr (1.3 × 10⁻⁶ atm).
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760 torr = 1 atm exactly
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120 mmHg systolic pressure
Exactly 760 torr. This is the definition of the standard atmosphere.
Atmospheres = torr ÷ 760. This is an exact conversion by definition.
Nearly identical. 1 torr is defined as exactly 1/760 atm (133.322 Pa), while 1 mmHg depends on mercury density and gravity (133.322 Pa at 0°C under standard gravity). The difference is negligible for practical purposes.
1 torr = 133.322 Pa (= 101,325/760 Pa). This is approximately the pressure exerted by 1 mm column of mercury.
Evangelista Torricelli (1608–1647) was an Italian physicist who invented the mercury barometer in 1643. He demonstrated that atmospheric pressure supports a column of mercury about 760 mm high.
1 torr is considered rough vacuum. Medium vacuum starts at about 1 torr, high vacuum at 10⁻³ torr, and ultra-high vacuum at 10⁻⁹ torr.
Normal blood pressure is 120/80 mmHg (torr): 120 torr systolic (heart pumping) and 80 torr diastolic (heart resting). This is 0.158/0.105 atm.
Torr is the traditional unit for vacuum measurements. Vacuum pumps are rated by their ultimate pressure in torr, and leak rates are measured in torr·L/s.
380 torr = 0.5 atm exactly (380/760). This is approximately the atmospheric pressure at an altitude of about 5,500 meters (18,000 feet).
Absolute pressure cannot be negative — zero torr represents a perfect vacuum. However, gauge pressure (relative to atmosphere) can be negative, indicating a partial vacuum.
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