How Big Do Jack Russell Terriers Get? Average Size Of JRTs

How Big Do Jack Russell Terriers Get? Average Size Of JRTs

The size of the dog is one of the most important facts that pet owners must pay attention to. Especially if you live in an apartment or a studio house, the size of the dog matters a lot.

Since Jacks are known as small dogs, most dog lovers and dog parents looking to adopt a JR and curious about the their size. This article is all about how big are Jack Russell Terriers and their height, weight, and more other facts related to the size.

So, How big do Jack Russell Terriers get? As we already know, JRTs are a small dog breed. A fully grown Jack’s average height may be around 10 – 15 inches, and their average weight is 12-17 pounds. These numbers might vary depending on their health and their pedigree.

I have listed below the main topics that I discuss about this breed in this post. Feel free to jump straight to the topic you want.

How big do Jack Russell Terriers get?

Since Jack Russel Terriers are small in size, their growth is unnoticeable. For instance, the growth of German Shepherds or Labradors puppies can be easily noticed, and owners can recognize when they are considered fully grown. 

The most common question that Jack Russel Terrier’s parents have is the exact age that they can consider their dog is fully mature or fully grown. The answer can vary, but generally, when a Jack Russel Terrier is 6-8 months old, you can consider it a fully grown dog.

If your dog has a healthy lifestyle with exercises, it can gain muscle and grow bigger in weight and height until it gets 12 months old. 

When a Jack Russell Terrier is fully grown average weight is 12-17 pounds, and height will range from 10-15 inches.

Read – All you need to Know about Jack Russell Terriers

Size of Male and Female Jacks

Size of Male and Female Jacks

Now you might be curious to know the size difference of the male and female Jack Russel Terriers. Usually, there is no considerable difference between the sizes of males and females Jack Russell Terriers. But there is a size difference among different Jack Russell Terrier breeds. 

While Jacks are 12-17 pounds weight, Russell Terriers are 11-16lbs, and Parson Russell Terriers are 13-17lbs weight. Also, Jack Russells are taller than Parson Russell Terriers and Russell Terriers. Parson Russell Terriers are the shortest among above mentioned 3 breeds.

Is a Jack Russell Terrier considered a small dog or a medium dog?

When someone thinks how big are Jack Russel Terriers, the next question they ask is if Jack Russell Terriers considered medium dogs? Jack Russell Terriers are considered small dogs. 

Although technically Jack Russell Terriers are small dogs, smaller dogs do exist. However, if you like to have a lap dog you can adopt a Jack Russell Terrier. But the most important thing is that dog training is essential. 

Since Jack Russell Terriers are small in size you can easily keep it in your apartment and it is an excellent family dog and you won’t regret adopting a Jack Russell Terrier.

Read – Jack Russell’s Old Age Problems – How to Care Guide from here.

What helps for Jack Russel Terriers’ growth and size?

How big are Jack Russell Terriers is based on some facts such as diet, exercises, and genetics. Therefore, it is very important to pay your attention to these facts as a Jack Russell Terrier Parent or dog lover. 

You may like to read – How long do Jack Russell Terriers live? A helpful guide for a longer lifespan

Diet is the most important thing in a dog’s life and as the owner it is your responsibility to give your dog a healthy and balanced diet. It is the main reason for your dog’s growth. Therefore, try to give your dog a healthy diet and if you give him dog food, go for branded and trusted food. No matter the food you give him, always check the nutritions of the food.  

Exercise is very important for Jack Russell Terriers. This is also a key reason behind its size and growth. It helps them to stay healthy and burn their energy and extra fat if they have some. Since the Jack Russell Terrier is a strong dog breed, they have the ability of doing exercises daily and it is your responsibility to give them some time to do exercises. 

Read – Why Do Jack Russells Shake? Reasons and Curing Guide

When you think about how big are Jack Russell Terriers, you might wonder about the genetic reasons behind this. Genes is also a reason behind your Jack Russell Terriers’ size. If you are going to adopt a Jack Russell Terrier, you can get an idea of your dog’s fully grown size by looking into its parents. 

If your Jack Russell Terrier is in good health condition, it helps your dog to grow to his maximum weight and height. As the owner, you can constantly pay attention to your dog’s health condition and don’t forget to keep records of his health issues, vitamins, vet visits, and other health condition related situations. 


From this article, we discussed all the reasons behind the size of the Jack Russell Terriers and their average weight and height. If you have a Jack Russell Terrier now, you can measure your dog’s size and do the necessary if he is below the average size. If you are looking forward to having a Jack Russell Terrier, don’t forget to check the size of the parents before you have your Jack Russell Terrier puppy. 

Read – Jack Russell’s Litter Size

We hope you enjoyed our article and gain knowledge about how Big are Jack Russell Terriers. Keep reading our blogs about different breeds of Jack Russells, and stay tuned for more articles.


  • George Brown

    George B. is the founder of the JRO Organization. He believes in creating a better world for domestic animals. He believes domestic animals are more vulnerable than other animals, especially dogs, since they have been used to depending on their owners for generations. So, he started JRO to share his ideas and insights while helping vulnerable dogs worldwide. George runs multiple projects on street dogs in developing countries, especially Sri Lanka.

    [email protected]

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