Use this Mastiff puppy weight calculator to predict how big your puppy will get. Mastiffs are a giant 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 8 lbs |
| 2 Months | 10 to 23 lbs |
| 3 Months | 18 to 46 lbs |
| 4 Months | 30 to 69 lbs |
| 5 Months | 42 to 92 lbs |
| 6 Months | 54 to 115 lbs |
| 7 Months | 66 to 138 lbs |
| 9 Months | 78 to 161 lbs |
| 10 Months | 90 to 184 lbs |
| 1 Year | 102 to 207 lbs |
| 1.5 Years | 114 to 230 lbs |
| 2 Years | 120 to 230 lbs |
Estimated from typical giant-breed growth curves and the Mastiff'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.
Mastiffs are prone to hip and elbow dysplasia given their extreme size and weight, and carry a notably elevated bloat (GDV) risk from their deep chest — splitting meals and restricting exercise around mealtimes matters. Giant breeds including Mastiffs also face an unfortunately short average lifespan, often just 9-10 years, with elevated cancer risk contributing to that.
Mastiffs need substantial food volume given their size, but portion timing matters as much as amount — 2-3 smaller meals a day rather than one large one, with exercise restricted for an hour before and after eating to reduce bloat risk.
The short coat needs minimal brushing, but skin folds around the face and neck need regular cleaning to prevent moisture-trapped infections.
Early socialization and obedience training matter enormously given this breed's eventual size — a giant breed that isn't well trained is a much bigger practical problem than a small one. Mastiffs are generally docile and respond well to calm, consistent handling.
The Mastiff (English Mastiff) is one of the most ancient dog types, with mastiff-like dogs depicted in Mesopotamian art dating back to the mid-second millennium BC. The modern breed was stabilized in England in the 1880s from surviving lines, and the Mastiff has contributed to the development of numerous other mastiff-type breeds worldwide.
Despite an imposing size that makes the Mastiff among the largest dog breeds by weight, the standard temperament is docile and dignified — a gentle giant bred for calm, confident guarding rather than aggression.
