Atmospheric Pressure Units & Conversion Principles
Atmospheric pressure represents the force exerted by air molecules per unit area. Different scientific and aviation conventions utilize varying unit systems, all mutually convertible.
Standard sea level pressure is 29.92 inHg (1013.25 hPa / 1013.25 mbar). In the United States, barometric pressure in weather reports and aviation altimeters is reported in inches of mercury (inHg), while international science standardizes on hectopascals (hPa).
Barometric trends indicate oncoming weather: rapidly falling pressure forewarns approaching storms or cyclonic fronts, while steadily rising pressure brings fair skies.
This tool converts pressure values simultaneously across inHg, hPa, mmHg, atm, and psi.