Gigacalories to kilojoules converter on this page calculates how many kilojoules are in 'X' gigacalories (where 'X' is the number of gigacalories to convert to kilojoules). In order to convert a value from gigacalories to kilojoules (from Gcal to kJ) just type the number of Gcal to be converted to kJ and then click on the 'convert' button.