Jack Russells are small, tough and famously long-lived. Plenty stay lively into their teens.
A 5-year-old Jack Russell Terrier is about 36 in human years, and a 10-year-old is about 56.
In a 2024 study led by Dogs Trust, published in Scientific Reports, which looked at more than half a million UK dogs, half of Jack Russells lived to 13.3 or older. That's longer than dogs overall, and about the same as a person reaching 69.
| Dog age | Human years |
|---|---|
| 1 year | 15 |
| 2 years | 24 |
| 3 years | 28 |
| 4 years | 32 |
| 5 years | 36 |
| 6 years | 40 |
| 7 years | 44 |
| 8 years | 48 |
| 9 years | 52 |
| 10 years | 56 |
| 11 years | 60 |
| 12 years | 64 |
| 13 years | 68 |
| 14 years | 72 |
| 15 years | 76 |
| 16 years | 80 |
Jack Russells count as small dogs (up to 9kg when fully grown). Small dogs age the most gently. After the second birthday, each year adds about 4 human years. If yours is much lighter or heavier than usual, pick their actual size in the full converter.
Open the full converterLifespan figures: McMillan et al. (2024), Longevity of companion dog breeds: those at risk from early death, Scientific Reports. Age chart attributed to the American Animal Hospital Association.