Torr to Inches Of Mercury
Type a value in either box to convert between torr and inches of mercury. The factor is 0.0393701.
| Torr | Inches Of Mercury |
|---|---|
| 1 Torr | 0.03937 inHg |
| 2 Torr | 0.07874 inHg |
| 3 Torr | 0.11811 inHg |
| 5 Torr | 0.19685 inHg |
| 10 Torr | 0.393701 inHg |
| 25 Torr | 0.984252 inHg |
| 50 Torr | 1.968503 inHg |
| 100 Torr | 3.937007 inHg |
How to use
- Enter a value in the Torr field.
- The Inches Of Mercury figure appears immediately — no button to press.
- Typing in the Inches Of Mercury field converts back to Torr the same way.
- Use the reference table for the values that come up most often.
Torr to Inches Of Mercury formula
To convert torr to inches of mercury, multiply by 0.0393700689.
inHg = Torr × 0.0393700689
Why this factor: the torr and the inch of mercury are both defined against the pascal, so dividing one definition by the other gives 0.0393700689 directly. Both definitions are set out in full below.
To go the other way, divide by 0.0393700689 — or use the Inches Of Mercury to Torr converter, which is the same calculation reversed.
Worked example
Start with 760 Torr. Multiply by 0.0393700689 to get 29.921252 inHg.
760 Torr × 0.0393700689 = 29.921252 inHg
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 an inch of mercury?
An inch of mercury is the pressure of a one-inch mercury column, used for US barometric pressure.
Definition: About 3,386.389 pascals.
Where it is used: US weather barometric pressure, aircraft altimeter settings, and engine vacuum readings.
Torr vs Inches Of Mercury
The torr is a specialized unit while the inch of mercury is a US customary unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many inches of mercury are in a torr?
One torr equals 0.0393700689 inches of mercury.
What is the formula to convert torr to inches of mercury?
Multiply the number of torr by 0.0393700689. To reverse it, divide by 0.0393700689 instead.
How do I convert inches of mercury back to torr?
Divide by 0.0393700689, which is the same as multiplying by 25.4000063.
How many inches of mercury are in 10 torr?
10 Torr works out to 0.393701 inHg.
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.