Millimeters of water to kilobars conversion calculator above calculates how many kilobars are in 'X' millimeters of water (where 'X' is the number of millimeters of water to convert to kilobars). In order to convert a value from millimeters of water to kilobars (from mmH2O to kbar) just type the number of mmH2O to be converted to kbar and then click on the 'convert' button.