If one atmosphere is about 14.7 psia, what is the standard barometer reading at sea level equal to?

The standard barometer reading at sea level is defined to be 760 mm of mercury (Hg). This value corresponds to one atmosphere of pressure, which is approximately 14.7 psia (pounds per square inch absolute). The choice of 760 mm Hg as a standard is rooted in historical measurements and the properties of mercury as a liquid used in barometers.

Mercury's density allows it to create a practical column height for measuring atmospheric pressure, which is why this specific measurement has been held as a global standard. As atmospheric conditions are represented by this height of mercury, it reflects the standard pressure conditions experienced at sea level.

Other measurements, such as 750 mm Hg, 780 mm Hg, and 790 mm Hg, do not represent the standard conditions, as they indicate variations in atmospheric pressure rather than the defined standard at sea level. The value of 760 mm Hg remains universally accepted for standard atmospheric pressure references in scientific contexts.