There is no sure fire way to tell how big your dog will be exactly, however you can come up with a generally idea.
The first thing to do is to figure out the breed. If the dog is a mix try and find out at least one of the breeds. If you look up that breed on the AKC website the range of the height and weight of the dog's breed should be listed in the breed standard.
If you can look at the dog's parents size. Generally the puppy will only grow to about their size.
Dogs typically stop growing between 1 to 2 years of age, depending on their breed and size.
Neutering does not affect a dog's growth. Dogs typically stop growing around 1-2 years of age, regardless of whether they are neutered or not.
Puppies stop growing at around a year of age. Smaller dogs may finish earlier, bigger dogs may finish later.
One and a half to two years of age
Dogs normally stop growing at around 18 months, then they bulk up.
Most dogs have all of their teeth by 8 months of age. These teeth will continue to move and settle into their permanent positions until dogs are about 12 months old.
Presa Canario dogs, stop growing at around two years.
When you grow up you will stop growing.
They get upto 24.5-28in (62-71cm) tall and weigh about 110 lbs (50kg).
There is no way to stop growing taller. You will stop growing usually around the age of 18.
They go to the supermarket and from there, they are given to you!! : )
yOU CANT STOP THEM FROM growing but after about 8 months it will stop growing.