megaton

Megaton is a unit of explosive energy used primarily to express the yield of large nuclear and conventional explosions. One megaton equals 1,000,000 tons of TNT, approximately 4.184 petajoules. It is a standard in the TNT equivalence scale, alongside smaller units such as the kiloton (1,000 tons of TNT) and larger scales like the gigaton (one billion tons of TNT).

In practice, the megaton expresses energy release but does not by itself describe other effects of an explosion, such as blast shape, thermal radiation, or radioactive fallout. Those effects depend on device design, burst altitude, geology, and atmospheric conditions. For context, the 1961 Soviet test Tsar Bomba had a yield of about 50 Mt, making it the most powerful nuclear device ever detonated. Other tested devices have yields ranging from several kilotons to tens of megatons. For conventional high-explosive charges, expressions in megatons are rarely meaningful, since civilian-scale explosions are far smaller.

The concept arose in the 20th century as scientists adopted TNT as a convenient reference energy. The megaton remains a familiar measure in discussions of very large explosions, particularly in historical and strategic contexts, where it provides a rough sense of scale without detailing all physical consequences.