well im not an expert and i do not have any king snakes any longer but i use to have a banded cali king that was 4ft long and was eating 2 large rats a week. well i got rid of him due to the fact after i fed him the last week i had him 1 day later he got out of his enclosure while i was cleaning my timberland rattle snakes cage and got ahold of my rattle and ate him also lol. so then i was out of a rattler due to my king. he tried to get to all my other snakes so he had to go. make a long story short though he would eat 2 large rats a week and would have ate more if i allowed him to do so.