Atmospheres (atm) to Inches of mercury (inHg) Conversion
Atmospheres
The standard atmosphere (atm) is a unit of pressure defined as exactly 101,325 Pa, representing the approximate mean atmospheric pressure at sea level. It remains in use in chemistry for expressing gas pressures in thermodynamic tables and standard conditions (STP: 0 °C and 1 atm). One atmosphere supports a mercury column of exactly 760 mm — the basis of the mercury barometer invented by Torricelli in 1643. In deep-sea diving, pressure is expressed in atmospheres absolute (ATA).
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.
| Atmospheres (atm) | Inches of mercury (inHg) |
|---|---|
| 0.1 atm | 2.9921255579757 inHg |
| 1 atm | 29.921255579757 inHg |
| 2 atm | 59.842511159515 inHg |
| 3 atm | 89.763766739272 inHg |
| 5 atm | 149.60627789879 inHg |
| 10 atm | 299.21255579757 inHg |
| 20 atm | 598.42511159515 inHg |
| 30 atm | 897.63766739272 inHg |
| 50 atm | 1496.0627789879 inHg |
| 100 atm | 2992.1255579757 inHg |
| 1000 atm | 29921.255579757 inHg |
Frequently Asked Questions (FAQ)
How many inches of mercury are in 1 atmospheres?
1 atmospheres (atm) is exactly 29.921 inches of mercury (inHg).
How do I convert atmospheres to inches of mercury?
Multiply the value in atmospheres by 29.921 to get the result in inches of mercury. Or use the converter above — type any number and see the result instantly.