Estimated power of nuclear weapons first strike | megatons |

A "megaton" is the explosive energy released by one million tons of TNT. For comparison, the bombs dropped on Hiroshima and Nagasaki were 0.015 and 0.021 megatons, respectively. An equivalent megaton is a way of making the explosive energy of different warheads comparable. It weighs small warheads — in this case those with at most one megaton — more than large ones, because they are relatively more destructive.The exact number of countries' warheads is secret, and the estimates are based on publicly available information, historical records, and experts' estimates.The warheads included here are strategic ones — those designed for use away from the battlefield, such as against military bases, arms industries, or infrastructure.Only those strategic warheads are included that could be deployed — those that could be carried by ballistic missiles, bombers, and submarines in one strike.