Gigajoules to gigawatt hours converter above calculates how many gigawatt hours are in 'X' gigajoules (where 'X' is the number of gigajoules to convert to gigawatt hours). In order to convert a value from gigajoules to gigawatt hours (from GJ to GWh) type the number of GJ to be converted to GWh and then click on the 'convert' button.