Torr to Millimeters Of Mercury
An instant torr-to-millimeters of mercury converter, with the formula and a reference table below.
| Torr | Millimeters Of Mercury |
|---|---|
| 1 Torr | 1 mmHg |
| 2 Torr | 2 mmHg |
| 3 Torr | 3 mmHg |
| 5 Torr | 4.999999 mmHg |
| 10 Torr | 9.999999 mmHg |
| 25 Torr | 24.999996 mmHg |
| 50 Torr | 49.999993 mmHg |
| 100 Torr | 99.999986 mmHg |
How to use
- Enter a value in the Torr field.
- The Millimeters Of Mercury figure appears immediately — no button to press.
- Typing in the Millimeters Of Mercury field converts back to Torr the same way.
- Use the reference table for the values that come up most often.
Torr to Millimeters Of Mercury formula
Converting torr to millimeters of mercury is a single multiplication by 0.999999858.
mmHg = Torr × 0.999999858
Why this factor: the torr and the millimeter of mercury are both defined against the pascal, so dividing one definition by the other gives 0.999999858 directly. Both definitions are set out in full below.
To go the other way, divide by 0.999999858 — or use the Millimeters Of Mercury to Torr converter, which is the same calculation reversed.
Worked example
Take 100 Torr and multiply by the factor 0.999999858: the result is 99.999986 mmHg.
100 Torr × 0.999999858 = 99.999986 mmHg
The converter above does this for any value you type, in either direction.
What is a torr?
A torr is a vacuum-measurement pressure unit, defined as one 760th of a standard atmosphere.
Definition: Exactly 101,325/760 pascals, which is about 133.3224 Pa. Named after Evangelista Torricelli.
Where it is used: Vacuum systems, mass spectrometry, and semiconductor process chambers.
Worth knowing: Almost identical to the mmHg but not exactly equal — they differ by about one part in seven million, which matters only in precision metrology.
What is a millimeter of mercury?
A millimeter of mercury is the pressure exerted by a 1 mm column of mercury, still standard in medicine.
Definition: Defined as exactly 133.322387415 pascals.
Where it is used: Blood pressure readings, intraocular pressure, and respiratory gas pressures.
Worth knowing: Blood pressure is universally reported in mmHg even in fully metric countries — one of the most durable legacy units in medicine.
Torr vs Millimeters Of Mercury
The torr and the millimeter of mercury belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many millimeters of mercury are in a torr?
One torr equals 0.999999858 millimeters of mercury.
What is the formula to convert torr to millimeters of mercury?
Multiply the number of torr by 0.999999858. To reverse it, divide by 0.999999858 instead.
How do I convert millimeters of mercury back to torr?
Divide by 0.999999858, which is the same as multiplying by 1.00000014.
How many millimeters of mercury are in 10 torr?
10 Torr works out to 9.999999 mmHg.
Is there anything to watch out for with torr?
Almost identical to the mmHg but not exactly equal — they differ by about one part in seven million, which matters only in precision metrology.
How is the torr defined?
Exactly 101,325/760 pascals, which is about 133.3224 Pa. Named after Evangelista Torricelli.