English Mastiff puppy growth: milestones and weight estimates
How fast an English Mastiff puppy grows, illustrative weight estimates and the limits of predicting adult size.
A Mastiff puppy can go from under 1 kg at birth to more than 45 kg (100 lb) by six months, one of the steepest growth curves of any breed. Height is mostly reached by around 18 months, but chest, head and muscle keep developing until about three years. Your dog will look grown long before its joints behave like adult joints.
Feed a diet made for large and giant breed puppies, with controlled calcium and energy, and aim for slow, steady growth rather than a round, fast-growing puppy. Avoid stairs, jumping in and out of the car, and forced running during the first 18 months. Book a vet check if you notice limping that lasts more than a day or two, swollen joints, or front legs that seem to bow as the puppy grows.
English Mastiff puppy growth in numbers
Illustrative size-based model for a male English Mastiff, in kg, by age in months
| Age | Female | Male |
|---|---|---|
| 2 months | 5.8 kg | 7.6 kg |
| 3 months | 9.6 kg | 12.5 kg |
| 4 months | 14.5 kg | 19 kg |
| 5 months | 19.5 kg | 26 kg |
| 6 months | 24.5 kg | 32 kg |
| 7 months | 28.5 kg | 38 kg |
| 8 months | 32.5 kg | 43 kg |
| 9 months | 36.5 kg | 48 kg |
| 10 months | 40 kg | 53 kg |
| 12 months | 45.5 kg | 60.5 kg |
| 14 months | 50.5 kg | 67 kg |
| 16 months | 54.5 kg | 72 kg |
| 18 months | 58 kg | 76.5 kg |
| 21 months | 61.5 kg | 81 kg |
| 24 months | 63.5 kg | 83.5 kg |
| 30 months | 65.5 kg | 86.5 kg |
This is an editorial model scaled to a typical adult weight, not an observed breed average, a validated growth standard or a healthy-weight range. Do not adjust food to make a puppy follow this line. Discuss actual growth measurements with your vet.