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