The power of a nuclear explosion is expressed in terms of its relationship to TNT due to the enormous power possessed by a single nuclear weapon. The explosive energy available is equivalent to thousands of tons (kilotons) or even millions of tons (megatons) of TNT.

For example, if a nuclear explosion releases energy equivalent to 7,000 tons (7 million kilograms) of TNT, it is called a 7 kiloton blast.