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