Pascal to Torr Converter
Our free force pressure & torque converter handles pascal torr conversions. See tables, ratios, and examples for quick reference.
Pascal to Torr Converter
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Formula: Torr = Pascals / 133.322
Worked example โ 101,325 Pa = 760.0 Torr = 1 atm
Formula
Torr = Pascals / 133.322
Divide pascals by 133.322 to get torr. This factor comes from the definition: 1 atm = 760 torr = 101,325 Pa, so 1 torr = 101,325/760 = 133.322 Pa. To convert torr to pascals, multiply by 133.322. Torr and mmHg differ by only 0.0014%.
Worked Examples
Example 1: Converting Atmospheric Pressure
Problem:Standard atmospheric pressure is 101,325 Pa. What is this in torr?
Solution:Torr = Pa / 133.322 Torr = 101325 / 133.322 = 760.0002 Torr atm = 101325 / 101325 = 1.0000 atm mbar = 101325 / 100 = 1013.25 mbar
Result:101,325 Pa = 760.0 Torr = 1 atm
Example 2: Converting Vacuum Chamber Pressure
Problem:A vacuum chamber operates at 0.5 Torr. What is this in pascals?
Solution:Pa = Torr x 133.322 Pa = 0.5 x 133.322 = 66.6610 Pa atm = 66.661 / 101325 = 0.000658 atm mbar = 66.661 / 100 = 0.6666 mbar
Result:0.5 Torr = 66.6610 Pa = 0.6666 mbar
Frequently Asked Questions
What is the relationship between pascals and torr?
One torr equals exactly 133.32236842 pascals, based on the definition that one standard atmosphere (101,325 Pa) equals exactly 760 torr. Therefore, 101,325 divided by 760 gives the conversion factor. The torr is named after Evangelista Torricelli, who invented the mercury barometer in 1644. While the pascal is the SI unit of pressure, the torr remains widely used in vacuum science, blood pressure measurement, and certain industrial processes due to its convenient scale for those applications.
What is the difference between torr and mmHg?
The torr and millimeter of mercury (mmHg) are nearly identical but not exactly the same. One torr is defined as exactly 1/760 of a standard atmosphere, while one mmHg is the pressure exerted by a 1 mm column of mercury at 0 degrees Celsius under standard gravity. The difference is approximately 0.0014 percent (1 torr = 1.000014 mmHg), which is negligible for most applications. In medical contexts, blood pressure is typically reported in mmHg, while vacuum technology tends to use torr.
Where are torr measurements commonly used?
Torr is predominantly used in vacuum technology and science. Low vacuum systems (rough vacuum) operate at 1-760 torr, medium vacuum at 0.001-1 torr, high vacuum at 0.000001-0.001 torr, and ultra-high vacuum below 0.000001 torr. Semiconductor manufacturing, thin film deposition, and mass spectrometry all specify chamber pressures in torr. Blood pressure is measured in mmHg (essentially torr), and some weather reporting still uses torr or mmHg for barometric pressure alongside hectopascals.
How does the pascal relate to other SI pressure units?
The pascal (Pa) is the base SI unit of pressure, equal to one newton per square meter. Common multiples include the kilopascal (1 kPa = 1,000 Pa), the hectopascal (1 hPa = 100 Pa, used in meteorology), the megapascal (1 MPa = 1,000,000 Pa, used for material strength), and the bar (1 bar = 100,000 Pa). Standard atmospheric pressure is 101,325 Pa or 101.325 kPa. The pascal is a relatively small unit, which is why kilopascals and hectopascals are more commonly used in everyday applications.
How do I convert between common vacuum pressure units?
The key relationships are: 1 atm = 760 torr = 101,325 Pa = 1013.25 mbar = 14.696 psi. For quick mental math, 1 torr is roughly 133.3 Pa or 1.333 mbar. In vacuum work, you may also encounter microns (1 micron = 0.001 torr = 1 millitorr). To convert between any two units, first convert to pascals using the appropriate factor, then convert from pascals to the target unit. This two-step approach avoids the need to memorize direct conversion factors between all possible unit pairs.
Why does vacuum work use logarithmic pressure ranges instead of a linear scale?
Useful vacuum spans more than ten orders of magnitude, from atmospheric 760 torr down past 0.000000001 torr in ultra high vacuum, so a linear scale would compress almost the entire working range into invisibility. Each decade also corresponds to a distinct physical regime, changing the mean free path of gas molecules and the flow behaviour from viscous to molecular. Gauges are therefore specified by decade, and one gauge type rarely covers more than three or four decades accurately.
What is a micron of mercury and how does it relate to torr?
A micron, also called a millitorr, is one thousandth of a torr, so 1000 microns equals 1 torr and 1 micron equals about 0.1333 pascals. The name comes from a mercury column one micrometre high. Refrigeration and HVAC technicians work almost entirely in microns, commonly evacuating a system to 500 microns or lower before charging, because that level indicates moisture has boiled off. Multiply microns by 0.133322 to get pascals.
Why can absolute and gauge pressure readings differ by an entire atmosphere?
Absolute pressure is measured against a perfect vacuum as zero, while gauge pressure is measured against surrounding ambient pressure, so gauge zero sits near 101325 pascals absolute. Torr readings in vacuum science are always absolute, which is why a chamber at 1 torr is described as near vacuum rather than as a negative pressure. Adding local barometric pressure converts a gauge reading to absolute, and subtracting it does the reverse.
Which vacuum gauge type should I use for a given pressure range?
Capacitance manometers and mechanical gauges read pressure directly and stay accurate from atmospheric down to roughly 0.001 torr, and they are independent of gas species. Pirani and thermocouple gauges infer pressure from thermal conductivity and cover about 0.001 to 10 torr, but their calibration shifts with gas composition. Ionisation gauges, hot or cold cathode, are needed below roughly 0.0001 torr. Matching the gauge to the decade you actually operate in matters more than headline accuracy figures.
How does temperature affect a mercury based pressure reading?
Mercury expands as it warms, so a column of a given height exerts slightly less pressure at higher temperature. The millimetre of mercury is defined at 0 degrees Celsius under standard gravity of 9.80665 metres per second squared, so a reading from a real mercury barometer at room temperature needs a small correction toward that reference. The torr avoids the problem entirely, being defined as one part in 760 of a standard atmosphere, a fixed pressure with no temperature dependence.
References
Reviewed for accuracy by Manoj Kumar, Mathematics Educator ยท Editorial policy
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