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Mastiff Growth Chart

Male adult weight160–230 lb72.6–104.3 kg
Female adult weight120–170 lb54.4–77.1 kg

Mastiffs (English Mastiffs) are among the heaviest dog breeds — calm, massive, and devoted. Adults typically weigh 120–230 lb, with males heavier than females. Most reach adult weight around 24 months.

View weight chart (lb & kg)

Calculate Your Mastiff Puppy's Adult Weight

Enter your Mastiff puppy's age and current weight for an estimated adult weight range.

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Mastiff weight by age

Typical male and female puppy weight ranges by age, available in lb and kg. Individual puppies may vary.

Most Mastiff puppies approach adult weight around 24 months, although individuals may finish earlier or later.

Weight unit
Expected Mastiff puppy weight at key ages in lb or kg
AgeTypical male rangeTypical female range
2 months (8 weeks)17–54.3 lb7.7–24.6 kg12.7–40.1 lb5.8–18.2 kg
3 months (12 weeks)25–65.8 lb11.3–29.8 kg18.7–48.6 lb8.5–22 kg
4 months (16 weeks)32.2–76.1 lb14.6–34.5 kg24.1–56.3 lb10.9–25.5 kg
5 months (20 weeks)38.9–85.8 lb17.6–38.9 kg29.2–63.4 lb13.2–28.8 kg
6 months (24 weeks)45.3–95 lb20.5–43.1 kg34–70.2 lb15.4–31.8 kg
7 months (32 weeks)57.1–112 lb25.9–50.8 kg42.8–82.8 lb19.4–37.6 kg
9 months (40 weeks)68.3–128.1 lb31–58.1 kg51.2–94.7 lb23.2–43 kg
1 year (52 weeks)84.2–150.9 lb38.2–68.4 kg63.1–111.5 lb28.6–50.6 kg
18 months (78 weeks)115.7–196.2 lb52.5–89 kg86.8–145 lb39.4–65.8 kg
24 months (104 weeks)149.6–230 lb67.9–104.3 kg112.2–170 lb50.9–77.1 kg

These estimated ranges combine the breed's adult weights with a size-based growth curve. They are not measured breed-specific percentiles or health targets. Month labels are rounded approximations; use the week values for each row. How these weight ranges are calculated

Mastiff Growth Stages

Understanding the typical growth stages helps you know what to expect as your Mastiff puppy grows.

Neonatal

0–2 weeks

Puppies are born with eyes and ears closed, relying entirely on their mother. Rapid weight gain occurs during this period.

Socialization

3–12 weeks

Eyes and ears open. Puppies begin to explore, play, and learn social behaviors. This is a critical period for development.

Juvenile

3–8 months

Rapid growth continues. Puppies become more independent, start teething, and develop coordination.

Adolescent

8–18 months

Growth rate begins to slow. Puppies reach sexual maturity and may test boundaries. Muscle mass develops.

Young Adult

18–24 months

Growth is nearly complete. Your puppy is filling out and approaching adult proportions.

Adult

24+ months

Your puppy has reached their full adult size. Weight should remain relatively stable with proper nutrition.

Mastiff FAQ

How much will my Mastiff puppy weigh as an adult?

Most adult Mastiffs typically weigh between 120 and 230 lb. Males often reach 160–230 lb, while females usually finish at 120–170 lb.

At what age is a Mastiff fully grown?

Mastiffs usually keep growing until about 24 months, and may keep adding bulk into their third year.

How accurate is a Mastiff puppy weight chart?

Charts show typical trends, not guarantees — and this breed has the widest normal range of any. Track your individual puppy's curve with your vet.

Do male and female Mastiffs grow differently?

Enormously. Males can outweigh females by 60 lb or more and carry vastly heavier bone.

How much should I feed my Mastiff puppy?

Feed a giant-breed puppy formula in strictly measured meals. With growth this massive, overfeeding is genuinely dangerous for joints. Your vet should supervise the growth curve.

Similar breeds

Explore growth charts for other dogs in the same size category.