Kilo-electron volts to millijoules conversion calculator shown above calculates how many millijoules are in 'X' kilo-electron volts (where 'X' is the number of kilo-electron volts to convert to millijoules). In order to convert a value from kilo-electron volts to millijoules (from keV to mJ) type the number of keV to be converted to mJ and then click on the 'convert' button.