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