1 atmosphere => 29.92 in Hg /760 mm Hg => 1.01325 bar => 1013.25 mb => 101.325 kPa => 1013.25 hPa

1 mb = 100 Pa = 0.1 kPa = 1 hPa = 0.0295 inches Hg = 0.75 mm Hg.

Source: http://www.islandnet.com/~see/weather/eyes/barometer2.htm