 The unit of measurement called standard atmosphere (atm) is defined as .Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar, and the kilopascal (1 kPa = 1000 Pa), which is equal to one centibar.Meteorological forecasts typically report atmospheric pressure in hectopascals per the recommendation of the World Meteorological Organization.