Neapolitan Mastiff Puppy Weight Calculator

Calculate the adult weight for your Neapolitan Mastiff. Just type your puppy’s current weight and age, and see how big your puppy gets.

Neapolitan Mastiff Breed Profile & Growth Guide

Breed Overview

The Neapolitan Mastiff is a massive, ancient breed with roots tracing back to the Roman Empire. Developed in southern Italy, this breed was originally used as a guard dog to protect property and livestock. Known for its loose skin, deep wrinkles, and intimidating presence, the Neapolitan Mastiff is surprisingly affectionate and loyal with its family.

Despite their daunting appearance, Neos are calm, steady, and protective. They are naturally wary of strangers but not aggressive unless provoked. These dogs do best in homes where they can receive proper training and socialization from an early age.

Size Category: Giant
The Neapolitan Mastiff falls into the giant breed category. Adult males typically weigh 150–200 lbs, while females weigh 120–175 lbs. Due to their rapid and extended growth period, tracking growth is vital to ensure proper bone and joint development and to prevent conditions like hip dysplasia and panosteitis.

Neapolitan Mastiff Growth Chart & Weight Ranges

Age	Male Weight (lbs)	Female Weight (lbs)
4 weeks	10 – 15	9 – 13
8 weeks	22 – 30	18 – 26
3 months	45 – 55	40 – 50
4 months	60 – 75	55 – 70
6 months	90 – 110	80 – 100
9 months	120 – 140	100 – 120
12 months	140 – 170	120 – 150
18 months	160 – 190	130 – 165
24 months	150 – 200	120 – 175

Gender Differences:
Males typically weigh 20–30 pounds more than females and may appear bulkier with a broader head and chest.

How Much Bigger Will My Neapolitan Mastiff Puppy Get?

Most Neapolitan Mastiffs reach about 50% of their adult weight by 5 to 6 months of age, though their rapid growth continues well beyond that. They grow quickly in the first 12 months but continue to fill out until they are 18–24 months old.

Rule of Thumb:
To estimate adult size, double their weight at 6 months for a rough prediction.

Note:
As a giant breed, the Neapolitan Mastiff’s growth period is extended, and final adult weight and muscle development may not be complete until age 2 or later.

Learn more about Neapolitan Mastiff health from the American Kennel Club (AKC).

Neapolitan Mastiff Growth Tips

Nutrition

• Feed a giant breed puppy formula that promotes slow, steady growth to reduce the risk of orthopedic problems.
• Avoid high-calorie or overly rich diets that can accelerate growth and strain developing joints.
• Feed 3 meals per day until 6 months, then transition to 2 meals daily.
• Supplements like glucosamine and chondroitin may support joint health—check with your vet.

Exercise

• Avoid intense running or jumping during puppyhood. Their heavy bodies and growing joints are vulnerable to damage.
• Focus on moderate, low-impact activities such as short walks and playtime on soft ground.
• Controlled exercise helps strengthen muscles and reduce the risk of obesity.

Health Watch

Common growth-related health issues in Neapolitan Mastiffs include:

• Hip and elbow dysplasia
• Panosteitis (growing pains)
• Entropion (inward-turning eyelids)
• Joint laxity due to rapid growth