The Staffy shares its ancestry with the American Staffordshire Terrier and the American Pit Bull Terrier. Because of this, they have a lot in common. However, the main thing that distinguishes the Staffy from the other two terrier breeds is the size, the Staffy being noticeably smaller than the other two.
When Do Staffies Stop Growing?
During the first 12-18 months, Staffies reach their full height but will continue to fill out and get heavier until they are fully mature. A Staffy’s full maturity can be as early as two years old or as late as three years old.
Staffy Growth Stages
Staffy Puppy Weight Chart
Age | Weight (kg) | Weight (lbs) |
---|---|---|
3 Months | 4.7 – 6.9 kg | 10.9 – 15.2 lbs |
4 Months | 6.2 – 9.1 kg | 13.7 – 20 lbs |
5 Months | 7.7 – 11.2 kg | 17 – 24.7 lbs |
6 Months | 8.5 – 12.7 kg | 18.7 – 27.9 lbs |
7 Months | 9.2 – 13.8 kg | 20.3 – 30.4 lbs |
8 Months | 9.8 – 14.7 kg | 21.6 – 32.4 lbs |
9 Months | 10.2 – 15.4 kg | 22.5 – 34 lbs |
10 Months | 10.4 – 15.8 kg | 22.9 – 34.8 lbs |
11 Months | 10.7 – 16.2 kg | 23.6 – 35.7 lbs |
12 Months | 10.9 – 16.5 kg | 24 – 36.4 lbs |
When Do Staffies Fill Out?
Staffordshire Bulls often reach full height and adult size by the time they are 18 months old. The changes in your dog’s head are apparent as they grow older. As the muscles grow, the head and jaw change shape.
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While most purebred Staffies’ heads begin filling out around the age of 12 months or so, they may continue to grow until they are at least 18 months old or even longer; this is the typical growth pattern for a purebred Staffy. A female Staffy’s head will always be smaller than the male.
Ensure Your Staffy Reaches Its Full Size
When you take good care of your Staffordshire Bull Terrier, you can ensure that he grows to his full potential. An age-appropriate nutritious diet, regular doctor visits, adequate exercise, and a safe environment are necessities for your dog’s health.
Don’t Allow Your Staffy to Become Stressed
Stress can restrict your Staffordshire Bull Terrier puppy’s growth. For example, an anxious Staffy will have less desire to eat; they will lose weight instead of gaining muscle mass. Other concerns, such as behavioural ones, can arise due to chronic stress and anxiety.

Lack of sleep can also stress your Staffy; ensure their sleeping arrangements are comfortable. Your Staffy might need a crate in the early stages after you bring them home.
Stress and anxiety will weaken your Staffy’s immune system. Veterinarians say dogs with weakened immune systems due to stress cannot fight disease or infection.
Lack of exercise, both mental and physical, and boredom, will result in your Staffy becoming stressed and anxious. Spending time together walking your Staffy regularly, for example, will strengthen your relationship while also reducing stress, anxiety and undesirable behaviours like whining, chewing or barking.
What Age Is a Staffy Full Grown?
Staffies are medium-sized dogs and should achieve full size by 12 months, although it is not uncommon for them to take up to 18 months. Even though your Staffy will reach their full height by this age, they won’t gain the maximum weight and be fully mature until they are two years.
How Big Is a Fully Grown Staffordshire Bull Terrier?
A fully grown Staffy will grow to reach between fourteen and sixteen inches and weigh between twenty-four and thirty-eight pounds. Their average life span is between twelve and fourteen years.