Use this Bullmastiff puppy weight calculator to predict how big your puppy will get. Bullmastiffs are a large working breed that keeps growing until around 18-24 months.
Enter your puppy's current weight and age to predict their adult size
Estimates based on breed growth curves. Individual dogs vary with genetics and nutrition — check with your vet for a personalized read.
Slows fast eaters, can aid digestion, holds 4 cups dry or wet food — sized for giant breeds.
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| Age | Weight |
|---|---|
| Birth | 2 to 5 lbs |
| 2 Months | 8 to 13 lbs |
| 3 Months | 15 to 26 lbs |
| 4 Months | 25 to 39 lbs |
| 5 Months | 35 to 52 lbs |
| 6 Months | 45 to 65 lbs |
| 7 Months | 55 to 78 lbs |
| 9 Months | 65 to 91 lbs |
| 10 Months | 75 to 104 lbs |
| 1 Year | 85 to 117 lbs |
| 1.5 Years | 95 to 130 lbs |
| 2 Years | 100 to 130 lbs |
Estimated from typical giant-breed growth curves and the Bullmastiff's adult weight range. Individual puppies vary — use the calculator above for a prediction based on your puppy's actual current weight.
New breed data, growth tips, and puppy-parenting insights, plus our free printable puppy growth tracker.
Bullmastiffs are prone to hip dysplasia, and as a giant breed carry an elevated cancer risk, including a documented lymphoma risk that's been the subject of genomic research in the breed. Bloat is also a concern given the deep chest.
Bullmastiffs tend to stay at a good weight or run slightly heavy — a large-breed puppy formula through the growth period and portion-controlled adult feeding (split into two meals) both matter.
The short coat needs minimal brushing; skin folds around the face should be checked for irritation.
Bullmastiffs are intelligent but independent-minded, and early socialization matters given the breed's size and guarding instincts — exercise should stay moderate, since this breed doesn't have the stamina for long-distance running despite its strength.
The Bullmastiff was developed in 19th-century England by gamekeepers who needed a dog capable of catching and holding poachers without mauling them — a cross of roughly 60% Mastiff (for size and calm strength) and 40% Bulldog (for speed and aggression), nicknamed the "Gamekeeper's Night Dog." The Kennel Club recognized the breed in 1924, the AKC in 1933.
The standard describes a symmetrical, powerfully built dog of great strength, endurance, and alertness — a working guardian breed whose original job demanded silent tracking and controlled restraint rather than attack, which still shapes the breed's calm, watchful temperament today.
