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Torr Conversion Table
This comprehensive torr conversion table shows how various units relate to torr (mmHg), a unit of pressure based on the height of a mercury column. Use this reference for quick conversions between torr and other common pressure units.
| Conversion | To Unit | Multiplier |
|---|---|---|
| Torr to pascals | Pascals | 133.322 |
| Torr to kilopascals | Kilopascals | 0.133322 |
| Torr to bars | Bars | 0.00133322 |
| Torr to millibars | Millibars | 1.33322 |
| Torr to atmospheres | Atmospheres | 0.00131579 |
| Torr to psi | Pounds per square inch | 0.0193368 |
| Torr to cmH₂O | Centimeters of water | 1.35951 |
| Torr to inHg | Inches of mercury | 0.0393701 |
This torr conversion reference table provides accurate conversion factors for both SI and common pressure units. All values are based on internationally recognized standards for maximum precision in scientific and engineering applications.
What is Torr (mmHg)?
The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly 1/760 of a standard atmosphere. It is equivalent to the pressure exerted by a column of mercury exactly 1 millimeter high at 0°C under standard gravity. The unit is named after Evangelista Torricelli, who invented the mercury barometer in 1643. Torr is also commonly referred to as millimeters of mercury (mmHg).
Torr is widely used in medicine (especially for blood pressure measurements), vacuum technology, and meteorology. Our torr conversion tool helps you easily convert between torr and other pressure units. For example, 1 torr equals approximately 0.0193 psi or 133.322 pascals.
What is the SI of Torr?
Torr is not an SI unit, but it is accepted for use with the SI. The SI unit for pressure is the pascal (Pa), which is defined as one newton per square meter (1 Pa = 1 N/m²). All other pressure units in the metric system can be converted to pascals, making it essential for SI units conversion:
- 1 torr = 133.322 pascals
- 1 torr = 0.00133322 bar
- 1 torr = 0.0193368 psi
- 1 torr = 0.00131579 atmosphere
What is Torr Used For?
Torr is used in a wide range of applications across science, engineering, and medicine where precise pressure measurements are required. Though not an SI unit, torr provides a convenient scale for specific applications:
Medical Applications
Blood pressure measurements (in mmHg), intraocular pressure measurements, and other physiological pressures. For example, normal systolic blood pressure is around 120 torr (mmHg).
Vacuum Technology
Measuring vacuum pressures in industrial processes, research laboratories, and semiconductor manufacturing. For example, high vacuum systems operate at pressures below 10⁻⁶ torr.
Meteorology
Atmospheric pressure measurements, especially in weather forecasting and aviation. For example, standard atmospheric pressure at sea level is 760 torr (mmHg).
Scientific Research
Pressure measurements in physics and chemistry experiments, particularly in low-pressure environments. For example, measuring the vapor pressure of liquids at different temperatures.
Etymology and History
The term "torr" is named after Evangelista Torricelli (1608-1647), an Italian physicist and mathematician who invented the mercury barometer in 1643. Torricelli demonstrated that atmospheric pressure could support a column of mercury approximately 760 millimeters high, establishing the principle behind the barometer.
The unit was originally defined as exactly 1 millimeter of mercury (mmHg) at 0°C. In 1954, the definition was refined to be exactly 1/760 of a standard atmosphere, which is equivalent to 101325/760 pascals. This modern definition makes the torr a precisely defined unit, independent of the physical properties of mercury. Despite not being an SI unit, torr remains widely used in many scientific and medical applications.
Frequently Asked Questions
What is the difference between torr and mmHg?
There is no practical difference between torr and mmHg (millimeters of mercury). Torr is the official unit name, while mmHg describes what the unit represents - the pressure exerted by a 1mm column of mercury. Both terms refer to exactly the same quantity, with 1 torr = 1 mmHg. The term mmHg is more commonly used in medical contexts.
How do I convert torr to other pressure units?
Use our torr conversion calculators above, or multiply by the appropriate conversion factor. For example, to convert torr to pascals, multiply by 133.322; to convert torr to atmospheres, divide by 760. For detailed instructions on converting torr to pascals, visit our torr to pascal converter. Our tool also handles conversions like torr to psi and torr to bar with high precision.
Why is torr used in medicine?
Torr (mmHg) is used in medicine because traditional blood pressure measurement devices (sphygmomanometers) used mercury columns. The height of the mercury column directly corresponds to pressure in mmHg. Even though modern devices are electronic, the unit remains standard for blood pressure measurements. For example, a normal blood pressure reading is approximately 120/80 torr (systolic/diastolic).
Is torr an SI unit?
No, torr is not an SI unit. The SI unit for pressure is the pascal (Pa). However, torr is accepted for use with the SI system. It is defined as exactly 1/760 of a standard atmosphere, making it a precisely defined unit. While not SI, torr remains widely used in scientific and medical applications due to historical precedent and practical convenience.
What are common uses for torr conversion?
Torr conversion is essential in medical settings (blood pressure measurements), vacuum systems (industrial and laboratory applications), meteorology (atmospheric pressure), and scientific research (pressure measurements in experiments). Whether calculating pressure differentials in a vacuum chamber or converting blood pressure readings, our torr converter tool simplifies these everyday tasks.
How does torr relate to atmospheric pressure?
Standard atmospheric pressure at sea level is defined as exactly 760 torr (mmHg). This relationship forms the basis for one of the definitions of the torr unit. When atmospheric pressure is higher than standard, it will support a taller mercury column; when lower, a shorter column. For example, at higher altitudes where atmospheric pressure is lower, the mercury column in a barometer will be shorter than 760mm.
Can I convert very small or very large pressures in torr?
Yes, our torr converter handles both extremely small and large pressure measurements with precision. For ultra-high vacuum work, convert pressures in the range of 10⁻⁹ torr. For high-pressure applications, convert values in thousands of torr. Our smart rounding feature ensures readable results for all scales while maintaining scientific accuracy.
Is your torr conversion tool free to use?
Yes, our torr conversion calculator is completely free with no registration required. Simply enter your value, select your target unit, and get instant, accurate results. We believe precise pressure measurement conversion should be accessible to everyone, from students learning about pressure units to professionals working on complex engineering projects involving vacuum systems.