Torr (Torr) - Unit Information & Conversion
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What is a Torr?
Torr is a pressure unit = 1/760 atmosphere ≈ 133.322 Pa ≈ 1 mmHg. Named after Evangelista Torricelli (barometer inventor). Standard in vacuum technology, high vacuum systems, some medical uses. 760 Torr = 1 atm.
History of the Torr
Named in 1913 after Evangelista Torricelli (1608-1647), Italian physicist who invented mercury barometer (1643). Defined as exactly 1/760 atmosphere. Preferred over mmHg in vacuum technology for precision.
Quick Answer
What is a Torr? Torr is a pressure unit = 1/760 atmosphere ≈ 133.322 Pa ≈ 1 mmHg. Standard unit in vacuum technology and physics. Named after Evangelista Torricelli (barometer inventor). 760 Torr = 1 atmosphere at sea level. Use our pressure converter for conversions.
Definition
1 Torr = 1/760 atm (exactly) = 133.322 Pa = 1.333 mbar ≈ 1 mmHg (0.000015% difference)
Key relationships:
- 760 Torr = 1 atmosphere (exactly)
- 1 Torr ≈ 1 mmHg (virtually identical)
- 1 mTorr = 0.001 Torr (millitorr)
Common Uses
Vacuum Technology: High vacuum pumps, vacuum chambers, thin-film deposition. Physics Laboratories: Pressure measurement in evacuated systems. Chemistry: Vapor pressure measurements, distillation processes. Medicine: Blood pressure (often interchangeable with mmHg).
Real-World Examples
Vacuum Levels (Torr)
- Atmospheric pressure: 760 Torr (standard)
- Rough vacuum: 1-760 Torr
- Medium vacuum: 10⁻³ to 1 Torr
- High vacuum: 10⁻⁶ to 10⁻³ Torr
- Ultra-high vacuum: 10⁻⁹ to 10⁻⁶ Torr
- Extremely high vacuum: <10⁻⁹ Torr
Vacuum Applications
- Vacuum packaging: ~50-100 Torr
- Freeze dryer: 0.1-0.5 Torr
- Rotary vane pump (ultimate): ~0.001 Torr (1 mTorr)
- Turbomolecular pump: 10⁻⁸ to 10⁻⁹ Torr
- Electron microscope: 10⁻⁵ to 10⁻⁷ Torr
- Particle accelerator: 10⁻⁹ to 10⁻¹¹ Torr
- Outer space (LEO): ~10⁻⁶ Torr
- Outer space (deep): ~10⁻¹⁴ Torr
Blood Pressure (Torr = mmHg)
- Normal: 120/80 Torr (120/80 mmHg)
- Elevated: 120-129/<80 Torr
- Hypertension Stage 1: 130-139/80-89 Torr
- Hypertension Stage 2: ≥140/90 Torr
- Hypotension: <90/60 Torr
- Severe hypotension: <70/40 Torr
Atmospheric Variations (in Torr)
- Sea level (standard): 760 Torr
- High pressure system: 770-800 Torr
- Low pressure system: 730-750 Torr
- Hurricane: 670-700 Torr
- Denver (1,609m): ~630 Torr
- Mount Everest summit: ~253 Torr
Vapor Pressures (Chemistry)
- Water (0°C): 4.6 Torr
- Water (25°C): 23.8 Torr
- Water (100°C): 760 Torr (boiling point)
- Ethanol (25°C): 59 Torr
- Acetone (25°C): 230 Torr
- Mercury (25°C): 0.002 Torr
Torr Conversion Formulas
To Pascal:
To Kilopascal:
To Megapascal:
To Hectopascal:
To Bar:
To Millibar:
To Atmosphere:
To Technical Atmosphere:
To Millimeter of Mercury:
To Inch of Mercury:
To Pound per Square Inch:
To Kilopound per Square Inch:
To Kilogram-force per Square Centimeter:
To Kilogram-force per Square Meter:
To Millimeter of Water Column:
To Inch of Water Column:
Frequently Asked Questions
Almost identical: 1 Torr ≈ 1 mmHg (difference < 0.000015%) Torr: Defined as exactly 1/760 atmosphere (by definition) mmHg: Based on mercury density at 0°C and standard gravity Practical usage:
- Vacuum technology: Prefers Torr (more precise definition)
- Medicine: Prefers mmHg (traditional, familiar)
- Chemistry: Uses both interchangeably Conversion: For all practical purposes, treat them as equal. Torr to mmHg converter →
Convert Torr
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