English Mastiff Growth Stages
Size and Weight Timelines
For Males And Females


English Mastiff is a giant breed that has an unusual growth rate—they grow fast, but it takes longer for them to reach full maturity. If you're planning on breeding this dog, wouldn't it be great if you can get a clear picture of their growth timeline?

So, what is the projected size and weight of an English Mastiff? A full-grown dog has an average height of 70 to 91 cm (27 to 35.8 in). An average male weighs 161 to 220 lbs (73 to 100 kgs), while females weigh anywhere from 120 to 170 lbs (54.4 to 77 kgs). They grow fast, but the puppy stage takes 18 to 24 months—even after that, they'll still keep growing.

During the puppy stage, some will grow slower, while others hit their growth plateau earlier than their siblings. It can be confusing and disturbing for new breeders, but fret not, because we'll discuss this breed's growth stages in great detail below. Read More...

Pro-tip: Ever try lifting a Mastiff? Their weight can hurt not only your back but their joints when they hop down from cars, sofas or even your bed. To protect your back and theirs check out the best Mastiff ramps on Amazon.com now.

Three English Mastiffs growing


How Fast Do English Mastiffs Grow?

There's no way to know for sure how fast your pet will grow. Unlike other smaller breeds with small incremental size and weight gains during their development, this breed's growth depends on individual growth rates.

Some could be smaller than their siblings but would hit several random growth spurts, and end up larger than most dogs. Others may be bigger than most during the early stages but suddenly hit a growth plateau.

Growth discrepancy is common among giant breeds, and is one reason why it can be challenging to determine how fast your dog will grow. You can use the size of your dog's relatives to create a growth projection for your pet, but it still doesn't guarantee anything.

When Do English Mastiffs Stop Growing?

Mastiffs grow fast, but they'll hit full maturity slower than other breeds. It takes at least 18 months to make the closest "guesstimate" on how big your dog will grow. By this time, he'll reach a more stable growth rate, which may continue until your dog reaches four years old! The growth rate of adults won't be as fast as when they were puppies, but you'll still see noticeable changes in their size and weight.

We found some additional fascinating facts pertaining to when Mastiffs finally do stop growing in this article of ours.  


Does your Mastiff have issues with anxiety, destructive chewing, aggressiveness, jumping up, barking or fearfulness?
Brain Training For Dogs is an excellent online training course that
addresses these behavioral issues as well as dog training basics.


English Mastiff Puppy Growth Timeline

To keep you informed of the projected growth rate of your dog, we've compiled the averages of all ages until one year old. But before you skim through it, here are four things that you have to remember:

  • Your dog may be bigger or smaller than these averages.
  • Your dog may go through random growth spurts or plateau.
  • Your dog may keep growing beyond two years.
  • Health conditions can affect or stunt your dog's growth and development.

English Mastiff Weight & Height at 2 Months

  • Males weigh anywhere from 21 to 37 lbs (9.5 to 16.8 kgs), with a height of 12 to 15 inches (30.5 to 38 cm)
  • Females weigh anywhere from 16 to 32 lbs (7.25 to 14.5 kgs), with an average height of 11 to 13 inches (28 to 33 cm)

English Mastiff Weight & Height at 3 Months

  • Male puppies at this age weighs 35 to 55 lbs (15.9 to 24.9 kgs), with an average height of 14 to 17 inches (35.5 to 43 cm)
  • Females at three months weigh anywhere from 29 to 49 lbs (13.1 to 22.2 kgs) and will reach a height of 13.5 to 17 inches (34 to 43 cm)

This YouTube Video Will Give You An Idea
Just How Fast English Mastiffs Grow!...


English Mastiff Weight & Height at 4 Months

  • Males at four months old, will weigh anywhere from 50 to 70 lbs (22.7 to 31.75 kgs), and will reach a height of 16 to 20 inches (41 to 51 cm)
  • Female weigh between 40 to 60 lbs (18.1 to 27.2 kgs), with an average height of 15 to 19 inches (38 to 48 cm)

English Mastiff Weight & Height at 5 Months

  • Males will reach an average weight of 65 to 95 lbs (29.5 to 43 kgs) and a height of 17.5 to 22 inches (44.5 to 56 cm)
  • Females become noticeably smaller than males of the same age, weighing anywhere from 50 to 80 lbs (22.7 to 36.3 kgs), with a height of 16 to 20 inches (41 to 51 cm)

English Mastiff Weight & Height at 6 Months

  • Males weigh anywhere from 85 to 115 lbs (38.5 to 52.1 kgs), with an average height of 19 to 24 inches (48 to 61 cm)
  • Females will weigh between 65 to 95 lbs (29.5 to 43 kgs), with an average height of 17 to 21 inches (43 to 53 cm)

English Mastiff Weight & Height at 7 Months

  • Males at seven months old weigh between 110 to 140 lbs (50 to 63.5 kgs), with a height of 20 to 25 inches (51 to 63.5 cm)
  • Females weigh anywhere from 75 to 105 lbs (34 to 47.6 kgs) and will reach a height of 17.5 to 22 inches (44.5 to 56 cm)

Pro-tip: Mastiffs love dog crates as they provide not only a sense of safety but also helps with their potty training and is a great way to keep them out of trouble when not  supervised directly. Check out the best Mastiff crates from Amazon.com


English Mastiff Weight & Height at 8 Months

  • Males at 8 months will weigh anywhere from 120 to 160 lbs (54.5 to 72.5 kgs) and will reach a height of 20.5 to 26 inches (51 to 63.5 cm)
  • Females will be anywhere between 85 to 115 lbs (38.5 to 52.1 kgs), with an average height of 18 to 23 inches (46 to 58.5 cm)

English Mastiff Weight & Height at 9 Months

  • Male English Mastiffs at nine months will weigh anywhere from 135 to 175 lbs (61.2 to 79.4 kgs) and reach a height of 22 to 27 inches (56 to 68.5 cm)
  • Females at this age will weigh 95 to 125 lbs (43 to 56.7 kgs), with a height of 18.5 to 24 inches (47 to 61 cm)

English Mastiff Weight & Height at 10 Months

  • Males will start to make smaller gains at 10 months, weighing 145 to 185 lbs (65.7 to 84 kgs) and reaching a height of 22.5 to 27 inches (57 to 68.5 cm)
  • Females will also hit their growth plateau, with an average weight of 110 to 140 lbs (50 to 63.5 kgs) and a height of 19 to 24 inches (48 to 61 cm)

English Mastiff Weight & Height at One Year

  • Males are closing in on maturity at one year weighing 150 to 200 lbs (68 to 90.7 kgs) and reaching a height of anywhere between 23.5 to 28 inches (60 to 71 cm)
  • Females will weigh 120 to 160 lbs (54.4 to 72.6 kgs), with a height of 20 to 25 inches (51 to 63.5 cm)


How Big Do English Mastiffs Grow?

Mastiffs are truly giant dogs. They can grow so big that the American Kennel Club (AKC) doesn't have a maximum height and weight in its breed standard. Although we have the average height and weight for adult English Mastiffs on this page, it's still possible that your dog can grow way beyond these averages.

Equally interesting is why Mastiffs are so big in the first place. Check out this article of ours on this topic to learn why. Also on that page is a YouTube video of what has to be the largest Mastiff (250lbs) we've ever seen!

English Mastiff Full-Grown Weight

A full-grown male Mastiff weighs anywhere from 161 to 220 lbs (73 to 100 kgs). Females, on the other hand, are significantly smaller, with an average weight of 120 to 170 lbs (54.4 to 77 kgs). These figures make this breed one of the heaviest dogs in the world! 

How Tall Is a Full-Grown English Mastiff?

If we are to use the AKC's breed standard, this breed has a minimum height of 30 inches (76 cm) for males and 27.5 inches (70 cm) for females. However, some dogs blow the charts out of the water. Zorba, for example, is an English Mastiff that reached a height of 38 inches (96.5 cm) at the shoulder!

Conclusion…

English Mastiffs are huge with a lean, muscular build that takes longer to develop. This breed will reach full maturity at 18 to 24 months, but they'll continue to grow until four years old! From birth to their full size, however, there will be several random growth spurts and plateaus that can affect their size and weight.

It's really impossible to predict how big your dog will get just by looking at his previous gains. Your best bet to create a projected growth rate for your pet would be to look at his relatives, but even that doesn't guarantee anything!

Want More Info About English Mastiffs?
Then You’ll Love These Pages On Our Site…


  1. Mastiff Guide Home
  2. English Mastiffs Breed Info
  3. English Mastiff Growth Stages