How big does a Bullmastiff get?
A full-grown Bullmastiff is a giant dog, weighing about 90–130 lb as an adult.
- Adult weight
- 90–130 lb
- Also in kilograms
- 41–59 kg
- Size class
- Giant
As a giant breed, a Bullmastiff keeps growing for longer than a small dog — larger breeds reach their adult weight months later (Hawthorne et al., 2004). Expect steady growth well past the first year.
Weight varies within the Bullmastiff by sex, genetics and health, and mixed-breed dogs fall between their parents. This is a typical range, not a guarantee.
Verified on . Based on Wikidata — dog breed mass (property P2067) (Wikimedia Foundation, requête du 2026-07-22, licence CC0) and Body-Weight Changes during Growth in Puppies of Different Breeds (Hawthorne et al., Journal of Nutrition, 2004, vol. 134, p. 2027S). See the method.