Kilopascals to millibars conversion calculator shown above calculates how many millibars are in 'X' kilopascals (where 'X' is the number of kilopascals to convert to millibars). In order to convert a value from kilopascals to millibars (from kPa to mbar) just type the number of kPa to be converted to mbar and then click on the 'convert' button.