Inches of mercury (inHg) to Millimeters of mercury (mmHg) Conversion
Inches of mercury
The inch of mercury (inHg) is a unit of pressure equal to the pressure exerted by a column of mercury 1 inch (25.4 mm) high — approximately 3,386.39 Pa or 0.0334 atm. It is used in US aviation for altimeter settings (standard pressure is 29.92 inHg) and in US weather reports for barometric pressure. Pilots set their altimeters in inHg based on local barometric pressure to ensure accurate altitude readings.
Millimeters of mercury
The millimetre of mercury (mmHg) is a unit of pressure equal to the pressure exerted by a 1 mm column of mercury at 0 °C and standard gravity — approximately 133.322 Pa. It is the universal clinical standard for measuring blood pressure: normal adult blood pressure is approximately 120/80 mmHg (systolic/diastolic). The mmHg is also used in ophthalmology (intraocular pressure, normal ≈ 10–21 mmHg) and respiratory physiology.
| Inches of mercury (inHg) | Millimeters of mercury (mmHg) |
|---|---|
| 0.1 inHg | 2.54 mmHg |
| 1 inHg | 25.40 mmHg |
| 2 inHg | 50.80 mmHg |
| 3 inHg | 76.20 mmHg |
| 5 inHg | 127.00 mmHg |
| 10 inHg | 254.00 mmHg |
| 20 inHg | 508.0001 mmHg |
| 30 inHg | 762.0001 mmHg |
| 50 inHg | 1,270.0002 mmHg |
| 100 inHg | 2,540.0003 mmHg |
| 1000 inHg | 25,400.0033 mmHg |
Frequently Asked Questions (FAQ)
How many millimeters of mercury are in 1 inches of mercury?
1 inches of mercury (inHg) is exactly 25.400 millimeters of mercury (mmHg).
How do I convert inches of mercury to millimeters of mercury?
Multiply the value in inches of mercury by 25.400 to get the result in millimeters of mercury. Or use the converter above — type any number and see the result instantly.