Mastiff Weight Chart

How big do Mastiffs get? See their growth chart and ideal weight.

Adult Weight Range
90-105 lbs
Size: Giant

Mastiff Growth Chart

8 weeks
11.7 lbs
12%
3 months
29.3 lbs
30%
6 months
58.5 lbs
60%
9 months
78.0 lbs
80%
12 months
87.8 lbs
90%
18-24 months
97.5 lbs
100%

Is My Mastiff a Healthy Weight?

A healthy Mastiff should have a visible waist when viewed from above, and you should be able to feel (but not see) their ribs.

  • Ideal: Ribs easily felt, visible waist, tucked abdomen
  • !Overweight: Ribs hard to feel, no waist visible, rounded belly
  • Underweight: Ribs, spine visible, prominent waist

Frequently Asked Questions

How big does a Mastiff get?

A healthy adult Mastiff typically weighs between 90-105 lbs. They are considered a Giant breed.

When does a Mastiff stop growing?

Most Mastiffs reach their full adult height and weight by 18-24 months. However, they may continue to "fill out" with muscle for a few months after.

How much should a Mastiff puppy weigh at 3 months?

At 3 months old, a typical Mastiff puppy weighs approximately 29.3 lbs. Growth rates vary, so consult your vet if concerned.

How can I tell if my Mastiff is overweight?

A healthy Mastiff should have a visible waist when viewed from above, and you should be able to feel (but not see) their ribs through a thin layer of fat. If the waist isn't visible, ribs are hard to feel, or the belly sags, your Mastiff may be overweight. Consult your vet for an accurate body condition assessment.