Jack Russell Terrier Weight, Size & Lifespan
How big does a Jack Russell Terrier get?
A full-grown Jack Russell Terrier is a small dog, weighing about 11–13 lb as an adult.
- Adult weight
- 11–13 lb
- Also in kilograms
- 5–6 kg
- Size class
- Small
Jack Russell Terrier Size
As a small breed, a Jack Russell Terrier reaches its adult weight earlier than a large dog — smaller breeds finish growing sooner (Hawthorne et al., 2004).
Jack Russell Terrier Lifespan
How long does a Jack Russell Terrier live?
This figure is measured, not published. McMillan et al. (2024) followed 19,166 dogs of this breed in the United Kingdom and recorded 13,497 deaths, giving a median age at death of 13.3 years (95% CI 13.2–13.3 years).
The American Kennel Club has no breed page for the Jack Russell Terrier under the name this site uses, so there is no published life expectancy to set beside this. A median age at death is not the same thing as a life expectancy: it is the age half the studied dogs had died by.
Jack Russell Terrier Growth Chart
What a Jack Russell Terrier puppy weighs week by week, from the growth curve FEDIAF publishes (Nutritional Guidelines 2025, Table VII-8a) for a dog whose expected adult weight is 5.5 kg. It is an average, not a target, and it is only valid from 8 weeks to one year — FEDIAF notes that growth patterns show a certain individual variability. Read a row as the middle of a spread.
| Age | Weight | % of adult weight |
|---|---|---|
| 8 weeks | 4 lb (1.8 kg) | 33% |
| 10 weeks | 5 lb (2.3 kg) | 41% |
| 12 weeks | 6 lb (2.6 kg) | 48% |
| 14 weeks | 7 lb (3.0 kg) | 54% |
| 16 weeks | 7 lb (3.2 kg) | 59% |
| 18 weeks | 8 lb (3.5 kg) | 63% |
| 20 weeks | 8 lb (3.7 kg) | 67% |
| 24 weeks | 9 lb (4.1 kg) | 74% |
| 28 weeks | 10 lb (4.4 kg) | 79% |
| 32 weeks | 10 lb (4.6 kg) | 84% |
| 36 weeks | 11 lb (4.9 kg) | 89% |
| 40 weeks | 11 lb (5.1 kg) | 93% |
| 44 weeks | 12 lb (5.3 kg) | 96% |
| 48 weeks | 12 lb (5.5 kg) | 99% |
| 52 weeks | 12 lb (5.6 kg) | 102% |
Common questions
How much does a full-grown Jack Russell Terrier weigh?
A Jack Russell Terrier weighs 11–13 lb (5–6 kg) as an adult. That range is the mass Wikidata publishes for the breed under a CC0 license, re-checked here every week — it is a typical weight across many adult dogs, not a target for one dog.
Is a Jack Russell Terrier a small dog?
Yes — a Jack Russell Terrier counts as a small breed, going by the middle of its adult weight range (5–6 kg). The cut-offs between small, medium, large and giant are a common veterinary convention rather than one official standard, so a breed near a boundary can be described either way elsewhere.
When does a Jack Russell Terrier stop growing?
Earlier than a large dog. Hawthorne et al. (2004) measured that smaller breeds finish growing sooner, so a Jack Russell Terrier reaches something close to its adult weight before a big breed would. We don't publish a month-by-month figure, because no source gives one breed by breed — and an invented number would be worse than none.
Why is there a range instead of one weight?
Because the source publishes a range. Within any breed, weight varies with sex, genetics, build and health, and a mixed-breed dog usually falls between its parents' breeds. Narrowing 11–13 lb down to a single number would look more precise while being less true.
How long does a Jack Russell Terrier live?
This figure is measured, not published: McMillan et al. (2024) followed 19,166 dogs of this breed in the United Kingdom, recorded 13,497 deaths, and report a median age at death of 13.3 years (95% CI 13.2–13.3 years). The American Kennel Club has no breed page for the Jack Russell Terrier under the name this site uses, so there is no published life expectancy to set beside it — and a median age at death is not the same thing as a life expectancy.
Breeds of a similar size
Every dog calculator
- Dog Age Calculator — Your dog’s age in human years, the science-based way
- Puppy Weight Calculator — How big will your puppy get, by breed
- Dog Pregnancy Calculator — Your dog’s due date from her mating date
- Dog Calorie Calculator — How many calories your dog needs a day
- Dog Chocolate Toxicity Calculator — How much chocolate is dangerous for your dog, by weight
- Puppy Feeding Calculator — How much to feed a puppy, by weight and age
- Dog Benadryl Dosage Calculator — How much Benadryl you can give a dog, by weight
- Puppy Vaccination Schedule — Puppy shots by age, from the AAHA’s published guidelines
Weight varies within the Jack Russell Terrier by sex, genetics and health, and mixed-breed dogs fall between their parents. This is a typical range, not a guarantee.
Verified on . Based on Wikidata — dog breed mass (property P2067) (Wikimedia Foundation, query run 2026-07-22, CC0 license), Longevity of companion dog breeds: those at risk from early death — Supplementary Table S3 (McMillan et al., Scientific Reports (2024), 14:531, 584,734 UK dogs — Kaplan-Meier median survival for 155 breeds), Body-Weight Changes during Growth in Puppies of Different Breeds (Hawthorne et al., Journal of Nutrition, 2004, vol. 134, p. 2027S) and Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs (FEDIAF (European Pet Food Industry Federation), 2025 edition (growth curves Table VII-8a, growth energy VII-8b and VII-10)). See the method.