Spanish Mastiff Growth Chart
Expected weight by age, week by week
Spanish Mastiff puppies grow at a fairly predictable rate as a percentage of their eventual adult size. Use this table as a general guide - every puppy is different.
| Age | Male weight | Female weight |
|---|---|---|
| 4 weeks (~0.9 mo) | 5.7–7.5 kg (12.6–16.5 lb) | 5–6.5 kg (10.9–14.3 lb) |
| 8 weeks (~1.8 mo) | 10.4–13.6 kg (22.9–30 lb) | 9–11.8 kg (19.8–26 lb) |
| 12 weeks (~2.8 mo) | 17.2–22.4 kg (37.8–49.5 lb) | 14.9–19.5 kg (32.7–42.9 lb) |
| 16 weeks (~3.7 mo) | 23.4–30.6 kg (51.6–67.5 lb) | 20.3–26.6 kg (44.6–58.5 lb) |
| 20 weeks (~4.6 mo) | 28.6–37.4 kg (63.1–82.5 lb) | 24.8–32.5 kg (54.6–71.5 lb) |
| 24 weeks (~5.5 mo) | 33.8–44.2 kg (74.5–97.4 lb) | 29.3–38.4 kg (64.5–84.5 lb) |
| 28 weeks (~6.4 mo) | 38–49.6 kg (83.7–109.4 lb) | 32.9–43.1 kg (72.4–95 lb) |
| 32 weeks (~7.4 mo) | 41.6–54.4 kg (91.7–119.9 lb) | 36–47.2 kg (79.4–104.1 lb) |
| 36 weeks (~8.3 mo) | 44.2–57.8 kg (97.4–127.4 lb) | 38.3–50.2 kg (84.3–110.6 lb) |
| 40 weeks (~9.2 mo) | 46.8–61.2 kg (103.2–134.9 lb) | 40.5–53.1 kg (89.3–117.1 lb) |
| 44 weeks (~10.1 mo) | 48.4–63.2 kg (106.6–139.4 lb) | 41.9–54.9 kg (92.3–121 lb) |
| 48 weeks (~11 mo) | 49.9–65.3 kg (110.1–143.9 lb) | 43.2–56.6 kg (95.2–124.9 lb) |
| 52 weeks (~12 mo) | 51–66.6 kg (112.3–146.9 lb) | 44.1–57.8 kg (97.2–127.5 lb) |
Common questions
How much should a Spanish Mastiff weigh at 3 months old?
At around 12 weeks (3 months), a Spanish Mastiff puppy typically weighs about a third of their eventual adult weight - roughly 17.2–22.4 kg for males and 14.9–19.5 kg for females, based on this breed's adult weight range of 52–68 kg (male) and 45–59 kg (female).
When does a Spanish Mastiff stop growing?
Most Spanish Mastiffs reach close to their full adult weight by around 12 months old, though giant breeds can continue filling out in muscle and chest depth for several months after that. Larger breeds generally take longer to fully mature than smaller ones.
My Spanish Mastiff puppy seems small/large for their age, should I worry?
Individual puppies vary, and these figures are typical ranges, not strict rules - genetics, litter size, and nutrition all play a part. If your puppy is well outside these ranges, gaining or losing weight rapidly, or you're generally concerned, check with your vet rather than relying on any online chart alone.
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