Torr to Atmospheres Converter
Unit ConversionConvert torr to standard atmospheres. 1 torr is about 0.00131579 standard atmospheres, with a conversion table and the reverse conversion.
Atmospheres
Equivalent pressure in standard atmospheres
Atmospheres (Scientific Notation)
1.000000 × 10^0
The same result for very small or very large values
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SponsoredThis converter turns torr into standard atmospheres (Torr to atm). Enter a value and the result updates as you type. 1 torr is about 0.00131579 standard atmospheres.
The torr is used for vacuum work and in chemistry. The torr is defined as exactly 1/760 of a standard atmosphere. So the conversion is a simple division, and 760 torr is exactly 1 atm. Pressures below one atmosphere, such as a partial vacuum, come out as decimals of an atmosphere.
The result shows 0 for a negative entry, because absolute pressure, counted from a perfect vacuum, cannot be negative. The result is rounded to 6 decimal places.
How to Convert Torr to Atmospheres
To convert torr to standard atmospheres, divide by 760. For example, 380 Torr equals 0.5 atm.
To go from standard atmospheres back to torr, multiply atmospheres by 760.
Torr to Atmospheres Conversion Table
Common Torr values converted to standard atmospheres, rounded to 6 decimal places.
| Torr | Atmospheres |
|---|---|
| 1 Torr | 0.001316 atm |
| 10 Torr | 0.013158 atm |
| 100 Torr | 0.131579 atm |
| 250 Torr | 0.328947 atm |
| 380 Torr | 0.5 atm |
| 500 Torr | 0.657895 atm |
| 750 Torr | 0.986842 atm |
| 760 Torr | 1 atm |
| 1,000 Torr | 1.315789 atm |
| 1,520 Torr | 2 atm |
| 7,600 Torr | 10 atm |
Torr and mmHg
Torr and millimeters of mercury are often treated as the same unit, but they are defined differently. The torr comes from the atmosphere: 760 torr equals exactly 1 atm. The conventional millimeter of mercury comes from mercury density and standard gravity and is exactly 133.322387415 Pa, according to the IUPAC Green Book. That makes 760 mmHg about 1.00000014 atm, a difference of about one part in seven million.
The torr is named after Evangelista Torricelli, who measured air pressure with a column of mercury. Vacuum work also uses the millitorr (mTorr), one thousandth of a torr: 1 mTorr is about 0.0000013158 atm, so the calculator also shows the result in scientific notation.
Torr to Other Units
| Unit | 1 Torr Equals |
|---|---|
| Pascals | 133.322368 Pa |
| Hectopascals / Millibars | 1.333224 hPa |
| Kilopascals | 0.133322 kPa |
| PSI | 0.0193368 psi |
| Bar | 0.00133322 bar |
| Inches of Mercury (inHg) | 0.0393701 inHg |
High vacuum readings run to many zeros, such as 0.000001 torr, and the Scientific Notation Converter writes them as powers of ten. Gas calculations usually want atmospheres, which is the unit the Ideal Gas Law Calculator takes.
Frequently Asked Questions
How many torr are in 1 atm?
1 atm equals exactly 760 torr, by the definition of the torr.
How many pascals is 1 torr?
1 torr is about 133.322368 pascals, which is 101,325 divided by 760.
Is torr the same as mmHg?
Almost. 1 torr is about 133.322368 Pa and the conventional mmHg is 133.322387415 Pa, a difference of less than one part in a million. Most everyday work treats them as equal.
Is the Torr to Atmospheres factor exact?
The reverse direction is exact: 1 standard atmosphere equals exactly 760 torr. In this direction the factor has no finite decimal form, so 1 torr is about 0.00131579 standard atmospheres. The calculator uses the full value and rounds only the result it shows.
What happens if I enter a negative value?
It shows 0. Torr and atmospheres here measure absolute pressure from a perfect vacuum, so they cannot be negative. Vacuum levels are written as small positive numbers of torr instead.
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