Bottom: Little Boy dropped on Hiroshima. 9,700 pounds. Blast yield 15 kilotons of TNT. Top: Fat Man dropped on Nagasaki. 10,300 pounds. Blast yield 21 kilotons of TNT.
ICBMs now carry thermonuclear weapons (hydrogen bombs. ) Warheads yield blasts tens of times more powerful and can weigh as little as 800 pounds.