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How Big Do English Mastiffs Get? | English Mastiff Size

Updated: Nov 11, 2023


English Mastiff size changes... Think you've got what it takes??? They say to expect your Mastiff to grow 2 years UP and 2 years OUT.
English Mastiff size as a puppy
English Mastiff size as a puppy


English Mastiff size changes a lot, and I mean a LOT from birth to age one



At birth, English Mastiff puppies are large compared to newborn puppies of other breeds. But compared to what they will become, they are quite tiny. English Mastiff size changes a lot, and I mean a LOT from birth to age one. Above on the left, the pup is the daughter of the dog below. She is probably eight weeks or LESS in that photo, having already grown substantially since birth.


English Mastiff size as an adult
English Mastiff size as an adult


English Mastiff size at birth is relatively small compared to what they will become.



English Mastiffs are often born in very large litters. The most surviving puppies we have every had in a litter was twelve. Yes Mastiffs are giant breed dogs. But all those puppies have to squeeze into mamma's tummy. Our dogs are natural whelpers, so pups are born small enough to fit through the birth canal.



English Mastiffs grow UP for about the first two years of life.


I notice the most drastic size change during the first year of life. Mastiffs change from a cuddly puppy that can fit in your lap to an enormous puppy resembling a lanky adult. And guess what, this enormous puppy would still like to be your lap dog. But the pain might have you pushing their huge paws and heavy bodies off of you. Just wait till you have been stepped on my a grown Mastiff. Ouch.




English Mastiffs grow OUT until about around age four.

Expect your English Mastiff size to be tall and thin until about age two. Then watch your pup fill out until about age four.





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