The atomic bomb, formed my nuclear fission?
that was dropped by Americans on japan?
well first, there was 2 of them and to answer your question
HUGE
Atomic bombs are measured by the mega tonne. That is the
equivalent of 1 million tons of TNT. So a 50 mega tonne bomb is the
equivalent of 50,000,000 tonnes of TNT exploding. The actual size
of the bomb can be anything from a giant rocket to the size of a
suitcase