Weight King Cobras usually do not exceed 44 lb 20 kg in bodyweight In fact they don t get even close The Guinness weight record stands at 12 75 kg 28 lb 1 oz for a 4 39 m 14 ft 5 in specimen that died in the Bronx Zoo in 1973 The longest was a 5 72 m 18 ft 9 in specimen that died in the London Zoo in 1939 The Eastern Diamondback Rattlesnake is the largest heaviest venomous snake in the world at up to 15 4 kg 34 lb although this specimen was only 2 36 m 7 ft 9 in long