Irish Terrier Weight, Size & Lifespan
How big does an Irish Terrier get?
A full-grown Irish Terrier is a medium dog, weighing about 25–27 lb as an adult.
- Adult weight
- 25–27 lb
- Also in kilograms
- 11.3–12.2 kg
- Size class
- Medium
- Life expectancy
- 13–15 years
Irish Terrier Size
As a medium breed, an Irish Terrier reaches its adult weight earlier than a large dog — smaller breeds finish growing sooner (Hawthorne et al., 2004).
Irish Terrier Lifespan
How long do Irish Terriers live?
The American Kennel Club publishes a life expectancy of 13–15 years for the Irish Terrier, on its breed page. That is a figure for the breed, not a prediction for one dog — an individual Irish Terrier can fall on either side of it.
A second source measured it instead of publishing it. McMillan et al. (2024) followed 535 dogs of this breed in the United Kingdom and recorded 146 deaths, giving a median age at death of 13.5 years (95% CI 13.1–14 years).
The two roughly agree here, which is not always the case: on 34 of the breeds on this site the measured median falls outside the range the AKC publishes, in both directions. They are still not the same measurement — a life expectancy for the breed on one side, the age half the studied dogs had died by on the other.
Irish Terrier Growth Chart
What an Irish 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 11.8 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 | 7 lb (3.4 kg) | 28% |
| 10 weeks | 10 lb (4.3 kg) | 37% |
| 12 weeks | 11 lb (5.1 kg) | 43% |
| 14 weeks | 13 lb (5.8 kg) | 49% |
| 16 weeks | 14 lb (6.4 kg) | 54% |
| 18 weeks | 15 lb (6.9 kg) | 58% |
| 20 weeks | 16 lb (7.3 kg) | 62% |
| 24 weeks | 18 lb (8.1 kg) | 69% |
| 28 weeks | 19 lb (8.8 kg) | 75% |
| 32 weeks | 21 lb (9.4 kg) | 80% |
| 36 weeks | 22 lb (9.9 kg) | 84% |
| 40 weeks | 23 lb (10.3 kg) | 88% |
| 44 weeks | 24 lb (10.8 kg) | 91% |
| 48 weeks | 25 lb (11.1 kg) | 94% |
| 52 weeks | 25 lb (11.5 kg) | 97% |
Common questions
How much does a full-grown Irish Terrier weigh?
An Irish Terrier weighs 25–27 lb (11.3–12.2 kg) as an adult. That range is the weight the American Kennel Club publishes in the breed's official standard, re-checked here every week — it is a typical weight across many adult dogs, not a target for one dog.
Is an Irish Terrier a medium dog?
Yes — an Irish Terrier counts as a medium breed, going by the middle of its adult weight range (11.3–12.2 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 an Irish Terrier stop growing?
Earlier than a large dog. Hawthorne et al. (2004) measured that smaller breeds finish growing sooner, so an Irish 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 25–27 lb down to a single number would look more precise while being less true.
How long do Irish Terriers live?
The American Kennel Club publishes a life expectancy of 13–15 years for the breed, re-checked here every week. That is a figure for the breed, not a prediction for one dog: an individual Irish Terrier can fall on either side of it, and how a dog is fed, exercised and cared for moves the odds. A second source measured it rather than publishing it: McMillan et al. (2024) followed 535 dogs of this breed in the United Kingdom, recorded 146 deaths, and report a median age at death of 13.5 years (95% CI 13.1–14 years).
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Weight varies within the Irish 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 Breed weights — official AKC breed standards (American Kennel Club, breed pages, accessed 2026-07-29), Breed life expectancy — AKC breed pages (American Kennel Club, breed pages, accessed 2026-08-10), 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.