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How Big Does the Mastiff Get? (Explained)

All breeds of dogs grow to a certain weight, height, and length which are also known as their full-grown size, and Mastiffs are no different. Therefore, if you are a Mastiff dog owner, naturally you would be intrigued to know that how big your Mastiff will get.

So, let’s not make any more delays and learn rationales of this topic regarding Mastiffs.

How Big Does The Mastiff Get?

Mastiffs are muscular and large-sized dog breeds. A fully grown male Mastiff can grow about 36 inches in height and can weigh between 160-230 pounds. And the average size that a female Mastiff can reach is about 27-32 inches in height and the weight can have a range anywhere between 120-170 pounds.

As you know, Mastiffs have quite a lot of distinct breeds, such as English Mastiff, French Mastiff, Italian Mastiff, and others. So you may not know, how big do different breeds of Mastiff female and male grow when they reach their adulthood.

So here, the average size and weight of both female and male Mastiffs of different and popular breeds have been provided below.

Tibetan Mastiff:

Tibetan Mastiffs are lion-like large-sized dogs with a furry mane. You can expect an adult male Tibetan Mastiff dog to grow up to 26 inches more at their shoulder. And these fluffy big doggies will weigh around 90-150 pounds (41-60 kilograms).

Female Tibetan Mastiffs are huge as well. A grown female Tibetan Mastiff is 24 inches or more at their shoulders. And they will weigh as much as 70-120 pounds (32-50 kilograms).


According to American Kennel Club (AKC) standard, the standard height of an adult Bullmastiff is ranged in between 25-27 inches (64-69 centimeters) and weighs around 110-130 pounds (50-59 kilograms).

Female Bullmastiffs get as big as 24-26 inches (61-66 cm) in height and weigh 100-120 pounds (45-54 kilo).

English Mastiff:

Fully grown-up English Mastiffs are large-sized dogs too. The average size of an adult English Mastiff is 36 inches in height and its weight ranges between 160-220 pounds.

And a female English Mastiff will reach the height of 27-32 inches on average and weighs around 120-170 pounds.

Neapolitan Mastiff:

Neapolitan Mastiff dogs are pretty big as well. So a male Neapolitan Mastiff dog is anticipated to attain a height of 26-31 inches at its shoulders and upon reaching its adulthood, it will weigh between 150-200 pounds.

In terms of female Neapolitan Mastiff dogs, they grow up to 24-29 inches tall and weigh between 120-175 pounds. However, some Neapolitan Mastiff dogs can grow smaller or larger than the average size.

French Mastiff:

French Mastiffs (The Dogue De Bordeaux) are known as enormously strong guardian Mastiff dogs. According to AKC and European FCI, the breed standard of french Mastiffs says that a male French Mastiff grows as tall as 27 inches and weighs 110 pounds on average.

And female French Mastiffs are specified with a height between 23-26 inches and weight around 99 pounds.

Italian Mastiff:

Italian Mastiffs are muscular dogs as well. So it’s seen that a grown-up male Italian Mastiff will get a height of 25-27.5 inches. And female Italian Mastiffs will grow between 23.5-26 inches in height.

And in terms of weight, male Italian Mastiffs weigh about 92.6-110.2 pounds (42-50 kg), female Italian Mastiffs weigh around 83.8-99.2 pounds (38-45 kg).

Pyrenean Mastiff:

Pyrenean Mastiffs are a breed of larger-sized dogs. Both are males and females get quite big but there are slight differences between the size of males and females. The male Pyrenean can become as tall as 27-31 inches and they will gain weight as much as 140-200 pounds.

Whereas female Pyrenean Mastiffs’ height ranges between 24-30 inches and their weight ranges between 130-180 pounds.

How Big Is A Full Grown Mastiff?

A full-grown mastiff gets big as 35-42 inches (89-107 cm) in their overall standing height. And it achieves a withers height that ranges between 27-36 inches. When a Mastiff reaches its adult age, it will gain weight about 120-230 pounds on average (54-104kg).

And the total body length of grown-up Mastiffs is 44.5-53 inches (113-135 cm) on average.

To say specifically according to gender, a grown-up male mastiff achieves a withers height of 30-36 inches, and its weight ranges between 160-200 pounds. But some Mastiffs can gain more weight than 200 pounds.

And female adult mastiffs grow their withers height of 27-32 inches and their weight ranges somewhere between 120-170 pounds.

How Tall Can A Mastiff Get?

Withers is the tallest point of a dog’s body and it also makes the standard point that helps in measuring the standard height of a dog. So height measured on the basis of withers height of Mastiff dogs, a Mastiff can get tall about 36 inches on average (regardless of gender).

Besides, know that a male Mastiff can get as tall as 30-36 inches, and a female Mastiff gets tall around 27-32 inches.

Except for the height based on withers, dogs have another height which is measured based on their standing point. And based on Mastiffs’ standing point, the average height of them is between 35-42 inches.

How Much Does Mastiff Weigh?

On average, an adult Mastiff dog’s weight ranges between 120-230 pounds/54-104 kilograms (regardless of gender).

But if you want to know an adult Mastiff’s weight according to its gender, know that a make Mastiff can weigh somewhere around 160-200 pounds. However, some male Mastiffs can weigh more than 200, those will have a weight of 220-230 pounds.

And the average weight of female Mastiffs is 120-170 pounds.

Mastiff Growth Chart:

It’s reasonable if you prefer to read a whole growth chart rather than looking for certain answers regarding Mastiff’s growth at different ages.

So for your convenience, here is a growth chart of both male and female Mastiffs containing size and weight according to different ages of them have been provided below.

Age Size (Male) Weight (Male) Size (Female) Weight (Female)
8 weeks14-15 inches24-30 pounds13-14.5 inches20-30 pounds
3 months20-22 inches30-47 pounds19-21 inches35-47 pounds
6 months22.5-24 inches70-100 pounds21-23.5 inches70-90 pounds
9 months23.5-25 inches108-165 pounds22-24.5 inches95-125 pounds
12 months25-26.5 inches125-190 pounds23-26 inches110-150 pounds
14 months25.5-27 inches132-199 pounds23.5-26.5 inches115-157 pounds
18 months26-29 inches145-210 pounds24-27 inches119-160 pounds
3 years/24 months(Fully grown)30 inches+160-230 pounds27-32 inches120-170 pounds

**Note: All of these measurements of Mastiff’s size and weight is considered as the standard size and weight as per Mastiff’s age. None of them are precise and a Mastiff can be bigger/smaller and skinnier/healthier than the size and weight are given in the chart.**

At What Age Is A Mastiff Full Grown?

At around three years old age, a Mastiff is considered to be a full-grown dog. However, most of their joint development, bones, and muscles development occurs during a Mastiff’s first years of age.

But until a Mastiff reaches24 months old/3 years old age, he continues to hold on to his pup-like temperament and some of his bodily features also keep, transforming.

Besides, until a Mastiff regardless of female and male doesn’t achieve its standard and ideal weight, height, and overall body length which is evaluated as the standard size of Mastiffs according to AKC standard.

And 3 years old is the time when a Mastiff achieves its optimum size and becomes mature, therefore, it’s the time when a Mastiff is a fully grown dog.

When Do Mastiffs Stop Growing?

Generally, when a Mastiff dog reaches his adulthood at three years old age, he stops growing up both physically and mentally.

However, no scientific research has not been done accurately yet to provide the exact time period regarding when a Mastiff stops growing. It’s because some Mastiff dogs stop growing as soon as they reach two years old age.

By that time, they already are close to achieving their adult size.

But since most of the Mastiff dog owners have stated that their Mastiff has gained mental maturity and the standard size at three years old, so 3 years old is assumed as the time for a Mastiff to stop growing.

3 Factors That Can Affect The Size Of Mastiffs:

Mastiffs are large dogs and there are several factors that affect the growth of Mastiffs. If you are thinking about the factors that make Mastiffs so large-sized dogs, go through this section. Here top 3 factors that affect the size of Mastiffs have been explained.


Genes are the most apparent factor that affects directly a Mastiff’s overall size. If you peep into the history of Mastiff dog breeds, you will see that the giant Molossus dogs were the forefathers of Mastiffs.

So the genes of extremely large Molossus are running inside the Mastiffs, therefore, genetically Mastiffs are born to have a large size.


Just like any other dog breed, Mastiffs also take after their parents. So if the parents of Mastiff’s offspring are giant large-bodied dogs, naturally, the baby Mastiffs will grow up to the standard size determined for Mastiffs as they reach adulthood.


Gender is the other important factor that affects the size of Mastiffs. Male Mastiffs are expected to get bigger in size than female Mastiffs. Even male Mastiffs weigh a few pounds more than female ones.

Will My Mastiff Still Grow After Being Neutered/Spayed?

Be assured that your Mastiff will grow after being neutered or spayed. Because early neutering or spaying doesn’t stunt a dog’s overall growth or the standard growth he is expected to be grown up with.

However, neutering or spaying may create issues in the joints of your Mastiff as he is a large-sized dog breed. And the joint problem is quite common in large dog breeds.

Also, know that neutering/spaying can affect the growth of your Mastiff in the opposite way making him grow taller than his average height. As neutering or spaying causes a delay in the closure of the growth plate.

What Mastiff Breed Is The Biggest?

English Mastiff is the largest breed among all of the Mastiff dog breeds. Fully grown English Mastiffs reach the height range of 27-35 inches and they weigh about 200-230 pounds.

So, both in the terms of height and weight, English Mastiff dogs are the biggest Mastiff dog breed alive in today’s date.

What Mastiff Breed Is The Smallest?

The French Mastiff or mononymously is known as the Dogue De Bordeaux is the smallest of all Mastiff breeds. A male French Mastiff only grows up to 27 inches and weighs inky 110 pounds. A female French Mastiff is even smaller in size.

Female French Mastiffs get a height of 23-26 on average and weigh about 99 pounds.

As French Mastiffs are the shortest in height and lighter in weight than other breeds of Mastiffs, therefore, undoubtedly they are the smallest Mastiff breed.

What Mastiff Is Right For Me?

The English Mastiff dogs are the friendliest and most gentle Mastiff dogs among the other ones. They make a great family dog because English Mastiffs are very easygoing by nature.

Also, they are fiercely loyal to their human families and their masters which also makes them the right dog for anyone who loves Mastiffs. English Mastiffs are child-friendly too

Besides, English Mastiffs are known as good pets for first-time owners as well. So all of these highly good qualities prove that an English Mastiff would be the best dog for you, even if you are a first-time dog owner.

What Mastiff Dog Breed Lives The Longest?

Tibetan Mastiffs live the longest among all other Mastiff dog breeds. On average, a Tibetan Mastiff dog gets a lifespan of 12-15 years which makes them the longest living Mastiff.

However, if they suffer from any health issue that might lessen the life expectancy of Tibetan Mastiffs.

Final Thoughts:

Being such a large-bodied dog breed, an adult Mastiff gets quite big. Especially the male Mastiffs are the largest ones with a total withers height of 30-36 inches and a weight of 160-230 pounds. Female Mastiffs also get 27-32 inches tall and weigh around 120-170 pounds. 

Frequently Asked Questions:

Why Is My Mastiff Limping?

Why Does My Mastiff Smell So Bad?

How to Make a Mastiff Gain Weight?

Why Do Mastiffs Howl, Whine & Cry So Much?

How High Can a Mastiff Jump?

Do Mastiffs Have Webbed Feet?