Watt hours to nanojoules conversion calculator shown above calculates how many nanojoules are in 'X' watt hours (where 'X' is the number of watt hours to convert to nanojoules). In order to convert a value from watt hours to nanojoules (from Wh to nJ) just type the number of Wh to be converted to nJ and then click on the 'convert' button.