English Mastiff Growth Chart & Size Guide – Plus 4 factors that May Impact Growth

The Old English Mastiff is a variation of the Mastiff breed (and is commonly simply referred to as “the mastiff”). These gentle giants were once bred for dogs of war and have in more recent times been used as guard dogs on wealthy estates across the UK. 

Many inexperienced owners can feel intimidated by the English Mastiff, simply because of its imposing physique. But just how big do English Mastiffs grow? And how much do Mastiffs weigh?

Well, the short answer is “huge”. The English Mastiff is one of the largest dog breeds in existence. It still holds the record for the largest dog ever, won by Zorba many years ago. 

So if you’re looking to welcome one of these majestic dogs into your home, you may be wondering if you have enough space to cater for this pooch. 

To help you with that, we have created an English Mastiff Growth chart. 

Age	Male weight	Male hight	Female weight	Female hight
2 months	29	13.5	24	12
3 months	45	15.5	39	13.5
4 months	60	18	50	17
5 months	80	20	65	18
6 months	100	21.5	80	19
7 months	125	22.5	90	20
8 months	140	23.5	100	20.5
9 months	155	24.5	110	21.5
10 months	165	25	112	22
11 months	170	25.5	115	22.5
12 months	175	26	120	23
14 months	185	27	125	23.5
16 months	189	28	126	24
18 months	192	29	129	25
2 years	205	29.5	135	26
3 years	220	30	150	27.5

Puppy Mastiff growth timeline

New-born To 2 Weeks 

At this time, the puppy will basically a blind and deaf blob that is totally dependent on its mother. In this period, responsible mastiff breeders will be very attentive to the mother, ensuring she’s eating and getting adequate rest. The puppies at this phase will be very demanding of milk which can take its toll on the mother. At the 2-3 week mark, puppies should start to open their eyes and develop their hearing. 

1 Month

As the one month mark approaches, the Mastiff puppies should start to demand less milk. Now is a good time to start the transition to wet food. Puppies develop considerably fast, their senses are now picking up as is their need to socialise and play with their litter siblings. At this time, the mother may also seek more “time outs” and rest from the group. 

2 Months

This point in time can also be an emotional period for the puppy as typically around the 8 week mark is when the puppy is starting to be separated from its mum. At this point they should be fully weaned off milk and have adapted to wet food. 

Obedience training should now be a priority for breeders and prospective new owners as this will set the early foundations for their ongoing behaviour. The puppies need to be house trained and socialised to not nip or jump up at strangers. Although many Mastiffs can pick this up quickly, owners should expect to be patient. 

The English Mastiff weight also grows considerably at this point with males averaging around 30 lbs and females at 25 lbs. Training whilst smaller means they’re less of a handful as they grow into their giant form. That said, their calm temperament and eagerness to please is always helpful. 

3 Months

The three month mark should see your puppy grow even further (roughly another 15 lbs). At this stage, owners should continue to develop their puppies’ socialisation skills. This means frequent introductions to people (friends, family) and other animals. 

Going for gentle walks will get your puppy used to a leash and harness which helps with building obedience. It’s also a good opportunity for them to meet other dogs and embellish their curiosities such as play and new smells. 

4 Months

Your puppy continues its g2g (growth to giant), likely stacking on another 15-20 lbs. Owners should look to keep developing the obedience and socialisation training, ensuring that they’re carefully nurturing a well behaved dog with a lovely nature. 

At this stage, your puppy will be gaining in confidence and be well adapted to its new environment. Now is a good time to consider puppy training classes to help further develop its socialisation skills. 

5 Months

Yet again, your puppy has probably put on another 15 lbs. They’re starting to come well adapted to basic obedience commands and socialisation. At this point, it’s likely that their bones will be more developed. Owners can look to slightly increase exercise and play. However, keep a close eye on their energy levels as you start to ramp this up. 

6 Months

Your Mastiff may be close to weighing 100 lbs at this point (female slightly less). They will be starting to put on more muscle in order to fill out that large frame. It’s well known that they can be a bit of a clumsy goof in this phase. It’s important to ensure your training and commanding presence are consistent so that the Mastiff sees you as the leader. 

7 Months

Your Mastiff should now be well adjusted to life. Its routine, environment and family are all extremely familiar and it is well behaved around other people and animals. 

8 Months

You should now have developed a strong bond between dog and owner. Your pooch is relaxed for the most part and you start to see those long admired Mastiff temperament qualities shining through. Calm, stoic but watchful. 

9 Months

As your bond strengthens with your Mastiff, you may start to notice bouts of separation anxiety when nobody is around. Owners should never leave their Mastiff alone locked away for extended hours on end as they can become overly sensitive to this and have the potential to become destructive and ill. 

10 Months

Your playful companion has packed on the pounds, perhaps 155 of them… At this phase, owners need to ensure that the dog is feeling stimulated. This means both physically and mentally. 

A 10-month-old English Mastiff can be very destructive if it doesn’t get adequate exercise and has no toys to play with. 

11 Months

At this stage, the Mastiff should start to feel like a confident member of the family. Owners may start to see some of their more protective qualities shine through as they keep watch. 

It’s important to ensure the dog is getting adequate exercise at this point and that energy is being expended. This is because the dog may now be approaching a weight of 160-170 lbs and we could do without that weight rambunctiously running about the place. 

1 Year

Your Mastiff may now be at 170 lbs +. They should be at one with their family and environment. By this point their personality should be fully developed and their nature should be calm. That early obedience training should be consistently applied from an early age. 

13 months & beyond

The Mastiff continues to develop into its frame, this can take up to three years which is longer than many other dogs. It’s likely that your Mastiff might not have fully developed its goofball nature until this point as well… Although, we do love the big slobbery child for this very fact. 

How big do English Mastiffs get?

This can be answered in a couple of different ways…

How much do mastiffs weigh?

By the time your English Mastiff is fully grown, it may reach up to 230 lbs in weight. However, there is a wide variance in sizes for this breed. With a male, you can expect anywhere from 160 lbs to 230 lbs. Females on the other hand are a bit smaller, reaching around 120 – 170 lbs. This is according to the AKC breed standard.

How Tall Do English Mastiffs Get?

An English Mastiff can grow to approximately 30” in height. Again, there is a wide range of variance in English Mastiff sizes. With a male, you can expect anywhere between 26.5″ to 30” tall. Females are once again a bit smaller, peaking at around 27.5”.

Did you know – The largest ever dog recorded was an English Mastiff named Zorba?

How Fast Do English Mastiffs Grow?

The English Mastiff grows very fast. Males tend to grow faster and larger than females. You can expect your English Mastiff to put on between 10 – 15 lbs each month up to the age of 10-11 months. 

Their growth rate tends to become slower after 11-12 months. However, the English Mastiff typically isn’t fully grown until 2-3 years old as it’s slower to mature than many other breeds.

Factors To Consider

There are different factors that can come into play when determining the size your English Mastiff will grow to. These are:

• Genetics
• Nutrition
• Neutering And Spaying
• General Health

How can genetics affect English Mastiff Growth?

It’s well known that the English Mastiff is a giant breed of dog. Their history and origin is that of a guardian or dog of war. They were bred for the very purpose of being large. However it’s common for your Mastiff to go through growth spurts and plateaus. 

The breed often has a large variance in weight and height. It’s quite difficult to determine how big yours will become. You may get an idea of size just by looking at the parents, but this still may not guarantee anything. Your best bet is to ask the breeder about previous litters and if they’re still in touch with previous buyers which may give you an indication.

How can nutrition affect English Mastiff Growth? 

The nutrition of your dog can have a large impact on how big it grows. The English Mastiff is known for its muscle bound physical appearance. This muscle needs a diet that is high in protein in order to properly develop. Alongside this, some healthy fats from occasional fish and marrow can help build a system. 

Outside of that, owners should make sure that the correct micronutrients are being absorbed by providing high quality and well established food. Avoidance of additives and preservatives can go a long way in ensuring a healthy gut and steady growth.

How can neutering and spaying affect English Mastiff Growth?

It’s unclear if neutering and spaying affects the growth of your English Mastiff. However, it has been suggested that it can lead to overgrowth of limbs which may create issues with joints as they age. 

It’s best to discuss the appropriate options with your vet. Typically females should be spayed after their first heat cycle and males should be neutered around the 2 year mark. 

How can general physical health affect the English Mastiff growth?

As with all dogs, there may be ongoing physical health conditions that may lead to growth issues. Perhaps your dog picked up a serious injury early in life or even more sinister conditions such as heart issues may impact a dog’s growth. 

Most Mastiff dogs come with health concerns such as joint issues, heart issues, bloat and so on. It’s best to keep an eye on this with your vet. If you have any concerns about growth rates then your vet may be able to offer you the correct guidance. 

Final Thoughts On English Mastiff Growth stages

As it matures, the Old English Mastiff is one giant lump of love. They are quick to pack on the pounds in puppyhood and you will be surprised at how fast they seem to grow right up until the 12 month mark. 

The Mastiff isn’t typically fully grown until three years, some suggest up to 5 years. This is a much longer period than many other dogs in the canine world. The Mastiff typically keeps some of its goofy traits right up to this point, although you will start to see the calm and relaxed, lounging tendencies come through from around the age of 9 months. 

Nutrition and lifestyle are key components on your Mastiffs growth journey. And although it may seem very expensive at times, investing in high quality food and activities such as play and socialisation contribute significantly to the overall wellbeing of your large companion. This in itself can help ensure your Mastiff grows to its full potential.

Frequently Asked Questions