The huge difference in yield of early nuclear weapons versus the most powerful ones ever tested is hard to grasp. The 1961 Tsar Bomba had a yield of around 4,000 times that of the Hiroshima bomb.This slide from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) already gives you a rough idea:

Scroll through to get a feel for it – but at your own risk of tendonitis for your mouse wheel finger!

Graphics by Joseph Blazkowicz.

One kiloton (kt) equals 1,000 tons of TNT (Trinitrotoluene) equivalent

Little Boy (Hiroshima Bomb): 15 kt

Fat Man (Nakasaki bomb): 21 kilotons

W80 warhead: 150 kilotons

Topol (SS25): 800 kilotons

Castle Bravo test (largest U.S. test, 1 March 1954): 15 megatons

Soviet Tsar Bomba (30 October 1961, largest test ever): 50 megatons

More on the Tsar Bomba @ CTBTO.org