Bar - is a widely used metric unit of measure for pressure and 1 bar converts precisely to 100,000 Pascals.
KPa - is a 1000x multiple of the Pascal unit which is the SI unit for pressure. 1 Kilopascal equals 1,000 Pascals.
MPa - is a 1000000x multiple of the Pascal unit which is the SI unit for pressure. 1 Megapascal equals 1,000,000 Pascals.
mbar - is a metric unit of pressure mainly used in European countries and is derived directly from the Bar pressure unit which equals 1,000 mbar. In SI units 1 mbar equals 100 Pascals.
Pascal (Pa) - is the SI unit for pressure and is derived from other SI units using the following relationships: Pa = (kg.m/s²)/m² = kg/m.s² = N/m². Since 1 pascal is a very low pressure being 1/100 of a millibar it's use is limited to ultra low pressure applications such as measuring the pressure differences in ventilation systems.
