Millimeters of mercury to millibars converter above calculates how many millibars are in 'X' millimeters of mercury (where 'X' is the number of millimeters of mercury to convert to millibars). In order to convert a value from millimeters of mercury to millibars (from mmHg to mbar) simply type the number of mmHg to be converted to mbar and then click on the 'convert' button.