The original U.S. estimate of the yield was 57 Mt, but since 1991 all Russian sources have stated its yield as 50 Mt. Khrushchev warned in a filmed speech to the Communist parliament of the existence of a 100 Mt bomb (technically the design was capable of this yield).The radius of the fireball (seen above) was 4 km, or a diameter of five miles. The energy released in the blast was roughly equivalent to ten times the entire firepower unleashed in WWII- including the two US fission bombs.
Yeah, that could ruin your day. (Hat tip to More Words, Deeper Hole)