It is a unit of measurement that does not belong to the International System of Measures. It is used to measure mass or also energy. As a measure of mass it is equivalent to 10 raised to the ninth power in tons or 1 . 000 . 000 . 000 (billion tons) . The equivalence is 10 to 15 grams (one thousand trillion grams). Energy released by the explosion of one Giga Ton of TNT. As a measure of energy equivalent to 4, 184×10 raised to the 18 power in Joules. 4 , 184 Trillion Joules .