Dog size guide
Dog lifespan by size
Reviewed: 2026-09-08 · Model: dog-lifespan-v0.1
Direct answer
In dog-lifespan-v0.1, size baselines are toy 14.2 years, small 13.2, medium 12.0, large 10.8, and giant 8.8 before individual adjustments.
Why size changes the baseline
Dog research consistently shows that larger adult size is associated with shorter average lifespan. PetLifeYears uses size as a high-impact factor in the dog model rather than borrowing cat logic.
Size is not the whole profile
Breed, current age, body condition, activity, neuter status, and chronic conditions can move the estimate within bounded limits.
- Toy baseline range: 12.0 to 17.0 years.
- Small baseline range: 11.0 to 16.0 years.
- Medium baseline range: 10.0 to 14.5 years.
- Large baseline range: 9.0 to 13.0 years.
- Giant baseline range: 7.0 to 11.5 years.
Use the calculator for a personalized educational range based on age, adult size, body condition, and health context.
Related guides
Sources and limits
Lifespan numbers on this page are traced to the listed source set or the versioned PetLifeYears model. They are educational planning ranges and do not replace veterinary advice.
- Frontiers in Veterinary Science / PMC: Life expectancy tables for dogs and cats derived from clinical data
- Scientific Reports: Life tables of annual life expectancy and mortality for companion dogs in the United Kingdom
- Companion Animal Health and Genetics / PMC: Lifespan of companion dogs seen in three independent primary care veterinary clinics in the United States
- Aging / PMC: Birth mass is the key to understanding the negative correlation between lifespan and body size in dogs
- American Animal Hospital Association: 2019 AAHA Canine Life Stage Guidelines