up to 800 grams. 2 mice adequate for there size twice a week. 801 grams and over. 1 adequately sized rat once a week. My yearlings have never refused food, and I could probably just keep feeding them all day if I had the mice but I wouldnt. I go based almost solely on size of stool. If the poop is huge I know I am either feeding to much or to often or a combo of both, again this is based on size of animal. I noticed a few weeks ago after tossing in a mouse another snake refused to my spider who already ate 2. Her poop the next time she went was way bigger than normal. So I stoped doing it. Figured if I eat way to much, I poop way bigger because my motabolism isnt keeping up with the amount of food I am putting in. I dont know if anyone understands this, but I am not crazy. I evaluate my snakes one at a time while they feed. Even had a live feeder get messed up by a rat this week and I had to literally flick the thing over and over again in the head to kill it. After awhile of watching my snakes eat and poop, eat and poop.(forever and ever) I have noticed slight differences from week to week. So each snake has a feeding car with exactly what weight pray they should be given down to the last gram....Boy, I have a feeling everyone is ganna think im crazy...maybe I am... STOP JUDGING THE CRAZY PERSON!!