Females get bigger than males (and depending on if it's a "black blood" or not) can get up to 6ft, and 40 lbs.
My 2-2.5 ft blood was taking between medium and large sized rats once a week, regularly, not skipping one meal. Once they get to adult size they will be eating large rabbits. Or 2 or 3 small rabbits...just depending on what you can get.
PERSONALLY (only my opinion) if you can't handle a burm, don't get a blood. They are really sensitive snakes, that tend to "hypervenilate" (looks like they breath really fast) if they get stressed, and tend to get RI easily if not taken care of exactly properly (if that makes sence) but if you are willing to put out the energy, time and money to learn to take care of it, go for it, they are georgeous snakes!
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1.1 Ball Python, 0.1 motley amel corn, 1.0 western hognose, 1.0 red blood