When Is My Bull Terrier Full Grown?

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I have a lot of fun with my Bull Terrier puppy. He’s just a pure ball of energy when I play. However, I’m wondering how long is he going to stay as a puppy. Eventually, he will grow bigger. When is my Bull Terrier full grown?

When Is My Bull Terrier Full Grown?

A Bull Terrier reaches its full size at the age of 20 to 24 months. It achieves its full height as early as 12 to 14 months. A male Bull Terrier grows bigger than its female counterpart, but no study shows that it grows bigger first than the females.

Graphic image of a brown and white Bull Terrier with a text explaining when Bull Terriers are fully grown

Average Size of a Bull Terrier

You might be planning to get a Bull Terrier but you’re wondering if the dog’s size would be compatible with your apartment’s space. Fortunately, Bull Terriers are one among other breeds that are best to have in your apartment. So, what is the average size of a Bull Terrier?

A Bull Terrier’s size varies, it generally differs according to its gender. Males are generally larger than female Bull Terriers. A female Bull Terrier has a size range of 50-60 pounds. On the other hand, a male one reaches the size of 60-70 pounds. They both stand between 21-22 inches.

A full-grown Bull Terrier grows between 35 to 75 pounds with a height range between 21 to 22 inches tall. A miniature Bull Terrier grows between 25 to 33 pounds with an average height of 10 to 14 inches. It depends on whether it’s a male or a female.

Bull Terriers are larger than their ancestors’ English Bulldogs or the British Bulldog. Male English Bulldogs only weigh 50 pounds while females weigh 40 pounds. Both have heights ranging between 14-15 inches tall.

However, their extinct Terrier ancestors are larger than Bull Terriers and Old English Bulldogs. The male weighs about 55-80 pounds, while the female weighs about 45-70 pounds.

This breed of dog reaches its full-grown stage at the age of 20-24 months old. Although both genders exhibit different sizes, there’s no evidence that proves one gender outgrows the other one.

Usually, a number of factors dictate the maturity of each dog upon reaching its full size.

Bull Terrier Development Stage

Watching your Bull Terrier grow is an exciting experience. From a cute little puppy to a full-grown adult, it exhibits major behavioral change. In the next section, I will discuss the different growth stages before a Bull Terrier reaches its full-grown size.

Bull Terrier sleeping on a pink stuffed toy

Neonatal Stage

A Bull Terrier’s neonatal stage starts from the day it was born until two weeks. Approximately, a two-week-old Bull Terrier weighs two to six pounds. During this stage, all its senses haven’t opened yet except its sense of smell.

A baby Bull Terrier would still have its eyes and ears closed. It’s usually unresponsive to human stimuli due to the lack of senses. 

However, a Bull Terrier puppy can only use its front legs to move and relies on its powerful sense of smell to locate its mother. Puppies are approximately 10,000 to 100,000 more sensitive than humans when it comes to their sense of smell.

Transitional Stage

The transitional stage happens between two to four weeks. The Bull Terrier will weigh six to 15 pounds. At this stage, a Bull Terrier puppy opens its eyes and ears. However, the sense of sight comes first before your puppy can hear.

The puppy’s eyes open right after two weeks, and the longest takes three weeks. If you notice that your puppy doesn’t open its eyes within the mentioned range, consult the vet as your puppy might be experiencing developmental problems.

At the start of the three-week mark, your Bull Terrier puppy should be able to respond to sound. The puppy’s ears open up within this period. Their hearing is far superior than mine.

A puppy can hear four times better and with a wider range of sound frequencies. It’s also during this stage that they start to grow their teeth.

Socialization Stage

At around four to 12 weeks, it will weigh 15 pounds to 50 pounds. A Bull Terrier will start to socialize with its littermates by playing. It begins learning how to interact that will shape its future.

This stage will also help build its personality when it turns adult. Slowly and gently expose your Bull Terrier puppy to various situations, places and people. It will help develop a calmer temperament when your dog encounters different situations and people.

Bull Terrier

Socialization is very important. Failure of doing so will cause behavioral problems in the future. Make sure to introduce new things with the right amount of praise and treats. Do it positively.

Ranking Stage

As your Bull Terrier turns three to six months has a size of 24 to 70 pounds. It will either dominate you or be submissive. It’s important to teach your puppy that you’re the dominant one. Dogs act on a hierarchical social structure. If they think they’re the alpha, they don’t follow rules.

As the owner, you need to assert yourself as the alpha leader. Bull Terriers that have strong alpha owners do well in obedience training. It helps prevent aggressive and destructive behavior. While teaching your dog that you’re the alpha leader, do it while having fun. Don’t force affection from your dog.

Always use positive reinforcement and avoid punishment.

Adolescence Stage

When your Bull Terrier reaches the age between six to 18 months, the adolescence stage starts. This stage is where your Bull Terrier reaches its full height that’s between 21 to 22 inches. It’s the stage where your dog starts to exhibit sexual behavior.

You can decide to neuter your dog within this stage. Your dog will also go through another teething stage and lose its puppy teeth. 

Full-Grown Miniature Bull Terrier

A Miniature Bull Terrier replicates the Standard Bull Terrier features but comes in a smaller version. A full-grown Miniature Bull Terrier weighs 23-33 pounds and stands 10-14 inches tall. Similar to bull breeds, it has a lot of muscle mass to its frame.

It has the right size for playing and cuddling.

The miniature size comes from the different ways of breeding. Miniature Bull Terrier undergoes three breeding stages. First, breeders pair a smaller breed to the dog.

Second, they would introduce a dwarfism gene to the dog. Third, they would keep on breeding from the smaller breed.

A Miniature Bull Terrier reaches its full size when it reaches the age of 11-12 months. However, it reaches its full height first when it turns 6-8 months old. Once a Miniature Bull Terrier reaches its full height, it doesn’t add any more bulk or muscle mass.

It reaches its full size slowly in comparison to other small dog breeds.

Maturity of a Bull Terrier

Bull Terriers have a wide range of mental maturity. It could range between one to fours years of age. A standard-sized Bull Terrier mentally matures at the age of 12-48 months. This breed of dog differs when it comes to maturity. On average, most of them mature when they turn two years old.

On the other hand, the Miniature Bull Terrier mentally matures when it turns 17 months old. In general, smaller breeds mentally mature the same time they reach their full size.

Maturity in a dog causes shedding off some of its puppy nature driven by the hormonal changes happening in its body. Some of the unpleasant or troublesome behavior calms down. You can also expect your dog to know how to calm itself more quickly and relax for a while.

Maturity brings confidence in your dog as he already experienced a lot of social interactions and has reached its full size.

As mentioned earlier, a mature dog displays social confidence only if socialized and trained well from a young age.

Social confidence is a positive trait as it gives you confidence as the owner that you can publicly take your dog out. However, in the case of a Bull Terrier, this breed of dog has an aggression issue when out in the public.

Be mindful of the existing breed-specific legislation on “bull-type” breeds implemented in your state.

Helping Your Dog Reach its Full-Size

Healthier Bull Terriers manifest a better chance of reaching their full-size potential. To help your Bull Terrier, ensure you provide appropriate food and exercise according to its age. Giving your dog food inappropriate for its age or doing too much at an early age can interfere with your dog’s growth plate.

For example, put a caution on your Bull Terrier puppy’s activities until your dog turns eight months old. Or if you have a miniature Bull Terrier, be cautious of its activities until it turns four months old. Their growth plates close during this stage.

Growth plates refer to soft areas found at the ends of a puppy’s long bones. These growth plates allow your dog to grow longer and dense.

Spaying or neutering is another way to help your Bull Terrier reach its full size. However, it’s crucial not to do it too soon. It’s best to consult your vet about the right age to neuter or spay your dog.

One danger of neutering your dog at a very early age can lead to deprivation of the important hormones your Bull Terrier needs to grow.

How Big Does a Bull Terrier Get?

A full-grown Bull Terrier grows between 35 to 75 pounds in weight with a height range between 21 to 22 inches tall. Usually, the female weighs 45 to 55 pounds while the male Bull Terrier weighs between 55 to 70 pounds.

A miniature Bull Terrier grows between 25 to 33 pounds with an average height of 10 to 14 inches. It depends on whether it’s a male or a female.

Is a Bull Terrier a Good Family Dog?

A properly socialized and trained Bull Terrier puppy makes a good family pet. However, buying a Bull Terrier as a first-time dog owner isn’t recommended. This breed of dog has incredible strength and can play rough with kids and other pets.

How Much Should a 4 Month Old Bull Terrier Weigh?

A four-month-old Bull Terrier weighs around 15-25 pounds for a male while a female Bull Terrier weighs between 10-20 pounds. Always measure the food you give your dog and never leave food in its bowl all the time. Obesity negatively impacts your dog’s life length.


In summary, your Bull Terrier reaches its full size when it turns 20 to 24 months. A Bull Terrier should have its maximum length ranging between 35-75 pounds and stands 21-22 inches tall. On the other hand, a miniature Bull Terrier should grow between 25-33 pounds with a height of 10-14 inches.

While your dog is still young, it’s fun to observe the development he exhibits as he grows in size. It’s important to be knowledgeable in these stages to assist your Bull Terrier in attaining its full size.