Inches of mercury to Atmospheres converter

To convert inches of mercury to atmospheres, enter the value in the first field. The result in atmospheres is calculated automatically using the exact conversion factor.

1 inHg ≈ 0.033421057393 atm
1 atm ≈ 29.9212555797 inHg

Formula: atm ≈ inHg × 0.033421057393
inHg ≈ atm × 29.9212555797

Definitions: 1 inHg = 25.4 mmHg; 1 atm = 101325 Pa

The inch of mercury (inHg) is the pressure at the base of a one-inch column of mercury. It is used in the United States for barometric pressure in weather reports and for altimeter settings in aviation, where standard sea-level pressure is 29.92 inHg.

The standard atmosphere (atm) is exactly 101,325 pascals, the average air pressure at sea level. It is a reference pressure in chemistry and physics and is used to express high pressures as multiples of atmospheric pressure.

See the conversion table with commonly used values, handy for quick reference or study.