Instructions
Research the breed. Visit reputable pet websites such as those for the American Bullmastiff Association and the American Kennel Club to see what the breed standard is for bullmastiffs. According to the AKC, male bullmastiffs will grow to be 25- to 27-inches tall and females 24- to 26-inches tall.
Ask your breeder for family history. When you purchase your bullmastiff pup, get information from the breeder about the heights of other dogs in that puppy's bloodline. Specifically, how tall are the puppy's parents? This will give you a good idea of how tall your pup will get.
Talk to your veterinarian. Vets are constantly evaluating all breeds of dogs and have a good sense of the proper size and weight of any given breed.
How to Determine the Height a Bull Mastiff Puppy Will Be
While puppies come in all shapes and sizes, knowing how large or small a puppy will be as an adult can help potential pet owners make the right decision about which breed of puppy to adopt. Bullmastiffs are large-breed dogs and therefore require more space than a Chihuahua, for example. By researching breed standards, you can get a good estimate on how big your bullmastiff puppy will be as an adult.