A purebred Bull Terrier puppy typically weighs around 10 pounds and stands 8-12 inches tall. The size of mixed breed puppies is more difficult to accurately predict. An average adult grows to about 22 inches in height and weighs anywhere from 52 to 70 pounds.
Bull Terriers are considered members of the large dog size class. This means that they grow faster than other smaller dogs, with their major growth spurt occurring between zero and five months old. These rambunctious and courageous dogs reach their full height and weight before their first birthdays and maintain their size for their full life expectancy, which is usually around 11-13 years.