Depends on its age and sex. Older calves weigh more than younger calves; male calves weigh more than heifer calves. Average birth weight is around 60 to 80 lbs.he average weight of a purebred Angus bull, at maturity, is ~2500 pounds. This depends on his diet, genes, and general health. There are a lot of mature Angus bulls that can … weigh well over 2500 lbs, and there are mature Angus bulls that will only weigh around 2000 lbs. 11 people found this useful.