Jack Russell Terriers can range in size as much as they can range in personalities.
Most individuals who are contemplating adopting a Jack Russell Terrier are likely curious about how big a full-grown Jack Russell will mature to.
How big is a full-grown Jack Russell?
I have been raising a Jack Russell for the past few years, and here is what I can tell you on this topic.
Jack Russell Terriers, on average, will range from 10-15 inches tall at the shoulder and weigh between 13-17 pounds when fully grown. Jack Russell Terriers can range in size and weight due to breeding and depending on if they are a mixed dog breed.
The rest of this brief post will detail what factors impact how big a Jack Russell Terrier will be when fully grown and some of the common heights and weights you can expect from different Jack Russell Terriers mixed breeds.
Here is how I intend to break this topic down for you:
- How Big Is A Full-Grown Jack Russell + Sizing for Male and Female Jack Russells?
- Average Weight and Height of Full-Grown Jack Russell Terrier’s (Based on Sex, Breed, and Mix)
- What Can Impact the Growth and Size of a Jack Russell Terrier
- Jack Russell Terriers Make for An Excellent Small Dog the Family Can Enjoy
How Big Is A Full-Grown Jack Russell + Sizing for Male and Female Jack Russells?
Jack Russell Terrier’s start small and adorable, and one of the best physical characteristics of the Jack Russell Terrier is that they remain small and adorable.
A common question that individuals ask about Jack Russells is when they can expect their Jack Russell to be considered full-grown.
Jack Russells are considered full-grown when they are 6-8 months of age.
Of course, this may vary with every Jack Russell as some Jack Russell Terriers may continue to fill-out of bulk up until they are about 1 year old.
Especially with routine exercise that is promoting a healthy lifestyle and muscle gain.
Assuming your Jack Russell Terrier is full-grown or between that 8-12 months of age, here is the height and weights you can expect to see.
Remember, this is the averages, and all Jack Russells are different.
Average Weight and Height of Full-Grown Jack Russell Terrier’s (Based on Sex, Breed, and Mix)
| Jack Russell or Terrier Breed | Height | Weight |
| Jack Russell Terrier Male | 10-15 Inches | 12-17 lbs |
| Jack Russell Terrier Female | 10-15 Inches | 12-17 lbs |
| Parson Russell Terrier Male | 12-14 Inches | 13-17 lbs |
| Parson Russell Terrier Female | 12-14 Inches | 13-17 lbs |
| Russell Terrier Male | 8-12 Inches | 11-16 lbs |
| Russell Terrier Female | 8-12 Inches | 11-16 lbs |
| Miniature Jack Russell Terrier Male | 8-10 Inches | 7-12 lbs |
| Miniature Jack Russell Terrier Female | 8-10 Inches | 7-12 lbs |
How Heavy Will A Jack Russell Get?
You can refer to the information in the table we just illustrated, but in general, a Jack Russell Terrier will reach about 12-17lbs in weight.
Some Jack Russells may be on the lower end of this weight, and some may push the higher end of the weight based on the diet, exercise, and muscle mass.
Again, all Jack Russells are different, but for the most part, you can bank on your Jack Russell weighing 12-17lbs.
If you are concerned about your Jack Russell being overweight, talk to your veterinarian so you can avoid any potential health issues.
The Size of a Jack Russell Terrier Puppy
When it comes to the size of a Jack Russell puppy, you genuinely have a pocket pet for the first 6 months or so.
A Jack Russell puppy that is 3 months old will weigh on average 6-8 pounds.
A Jack Russell puppy that is 6 months old will weigh 9-11 lbs.
Mixed Jack Russell Terriers May Vary in Height, Weight, and Size
You also need to keep in mind that Jack Russell Terrier mixes will vary in weight compared to your typical full-bred Jack Russell Terrier.
Here are some examples to give you an idea:
| Jack Russell Terrier Mix | Height (inches) | Weight (lbs) |
| Bo-Jack 1/2 Boston Terrier | 10-15 inches | 10-16 lbs |
| Jug 1/2 Pug | 10-15 inches | 8-13 lbs |
| Jack-A-Bee 1/2 Beagle | 10-16 inches | 15-35 lbs |
| Border Jack 1/2 Border Collie | 16-22 inches | 22-32 lbs |
| Jarcairn 1/2 Cairn Terrier | 11-12 inches | 11-12 lbs |
| Jack Chi 1/2 Chihuahua | 12-15 inches | 8-18 lbs |
| Cocker Jack 1/2 Cocker Spaniel | 13-20 inches | 15-30 lbs |
| Jackshund 1/2 Dachshund | 8-23 inches | 15-28 lbs |
| Rustrailian Terrier 1/2 Australian Terrier | 10-18 inches | 10-25 lbs |
| French Bull Jack 1/2 French Bull Dog | 11-14 inches | 13-28 lbs |
| Golden Jack 1/2 Golden Retriever | 10-15 inches | 13-19 lbs |
| Jack Russell and German Shepard | 13-14 inches | 14-20 lbs |
| Jack-A-Ranian | 12-15 inches | 6-14 lbs |
| Yorkie Jack 1/2 Yorkshire Terrier | 10-12 inches | 6-12 lbs |
| Husky Jack 1/2 Siberian Husky | 17-19 inches | 30-40 lbs |
| Jack-A-Poo 1/2 Poodle | 10-16 inches | 13-25 lbs |
| Papijack 1/2 Papillon | 10-15 inches | 8-15 lbs |
| Co Jack 1/2 Corgi | 10-13 inches | 18-28 lbs |
What Can Impact the Growth and Size of a Jack Russell Terrier
Something some of you may not know is that a few factors can even impact how much growth your Jack Russell experiences and how big they ultimately get.
I wanted to cover a few of those factors in this post:
Diet
While diet is unlikely to cause much of an impact on your Jack Russells growth, it could if it becomes an issue with a lack of nutrients or nutritional needs that your Jack Russell has to remain healthy.
You want to avoid your Jack Russell ever lacking any of these nutrients.
Stick with recommended and trusted brands for your dog food.
Genetics
As with most dog breeds, genetics plays a vital role in how big a Jack Russell will ultimately be.
If you adopt or adopted your Jack Russell Terrier from a local breeder near you, you can ask to meet the parents of your Jack Russell to get a better idea of how big your JR will grow too at full size.
Exercise Routines
Exercise may not stunt the height of your Jack Russell but can impact the muscle mass they develop which can ultimately impact the overall weight.
Jack Russell Terriers are a strong dog breed with broad muscles and broad chest bones.
They are also a hyper dog breed.
They need the ability to exercise every day, ideally to remain in optimal health.
Health Problems
Other health problems may be out of your control for the most part and should not be a significant factor in your Jack Russells growth but could potentially.
Be sure to always get your Jack Russell checked up by a certified vet once per year to ensure they are at peak health.
Is A Jack Russell Terrier A Small or Medium Dog?
This question could come down to debate.
The Jack Russell Terrier is technically classified as a small dog, but clearly, smaller dogs do exist.
If you are looking for a small dog that would be considered a lap dog, a Jack Russell Terrier is a good option for you.
Just be sure to exercise and tucker them out if you want them to relax during this cuddle time.
Jack Russell Terriers Make for An Excellent Small Dog the Family Can Enjoy
Hopefully, this brief post gave you insight into how big a Jack Russell will grow and what height and weights you can expect with your Jack Russell going forward.
They make for excellent family dogs.
If you are considering adopting a Jack Russell Terrier in the future, I highly recommend it and do not believe you will have any regrets.
Luna and I certainly wish you the best of luck with your new Jack Russells and the journey you have ahead of you.
Share Your Thoughts on Your Jack Russells Size, Weight and Height
How big did your Jack Russell grow to?
Be sure to share those thoughts, stories, and concerns by dropping a comment below.
As always, Luna and I appreciate you stopping by and reading today, and we will see you again next time.
For all the new owners reading, do not forget to check out and subscribe to our YouTube channel here.
We release videos every Tuesday and Thursday, answering questions and having fun with our Terriers.
Cheers.
