The SI derived unit of pressure. One pascal (Pa) is equal to 1 newton m⁻². The kilopascal (kPa) is the preferred unit for atmospheric pressure, but the more familiar millibar (mb) is the unit of pressure generally used by meteorologists, by international agreement; 1 mb = 1 hPa (hectopascal). For a typical sea level pressure, 102. 345 kPa = 1023. 45 hPa = 1023. 45 mb.