Standard atmospheric pressure at sea level is taken as 1013.2 millibars (mb), equivalent to 101.320 kPa in SI units. Barometric readings provide important data for weather prediction, in conjunction with temperature, wind velocity, and so on. The markings on the periphery of the dial give a rough indication of the expected weather—to be regarded, however, "with a grain of salt"!

Atmospheric pressure also depends on elevation above sea level, according to the approximate relation , where is the altitude in meters. It is assumed here that aneroid barometers are available for altitudes in intervals of 500 m.