Hello, I have never weighed my snakes as a determining factor in breeding but rather use age and a sense of healthiness. I will only breed rosys that are at least three years of age(I know it has been done successfully with younger but I don't do it). And as long as they have a good body weight I will go through with it. The males I am not so worried about with weight although sometimes if you are using one male with multiple females it may be something to consider if he drops off feeding during breeding season. I keep feeding logs so if I have a female that has missed some meals I opt out of breeding for that year then next year I concentrate on getting her to feed regularly and with maybe larger meals. hope this helps.