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Dog Lifespan Calculator: Your Dog's Senior Chapter, Mapped
Answer seven quick questions and get three things: when your breed's senior years typically start, the published lifespan range for dogs this size, and a Health Span Score that shows where your daily routine is already strong — and where a small change pays off. No sign-up, nothing to install.
What this calculator does — and what it never does
How the score works (short version)
The Health Span Score starts at 100 and subtracts documented penalties across five routine factors, with body condition weighted highest — excess weight is the routine factor most consistently associated with reduced lifespan and comfort in dogs (Kealy et al., 2002). The full factor table, band definitions, and version history live in the methodology page. Current model: v1.0.0.
FAQ
How long do dogs live?
It depends mostly on size: small dogs typically live around 12–16 years, medium dogs 10–14, large dogs 9–13, and giant breeds often 6–10. The calculator shows the published range for your dog's size — as context, never as a prediction for your individual dog.
When is my dog considered a senior?
It scales inversely with size: small dogs around 11 years, medium around 9, large around 8, and giant breeds around 7 — with breed-level variation. Once dogs cross their senior threshold, twice-a-year vet checkups are typically recommended (AAHA).
Can I actually extend my dog's life?
No calculator can promise that. What the evidence associates with better senior outcomes is a set of routine levers — keeping body condition lean, steady gentle movement, measured complete-and-balanced feeding, daily dental care, and regular vet visits. This tool scores where your routine already covers them.
My dog is a mixed breed. Which breed do I pick?
Any you like for context, or choose "Mixed / Rescue" and pick a size class — the senior age and range come from size, which is the dominant factor for mixed-breed dogs.
Why do you ask about dental care?
Periodontal disease is one of the most common conditions in adult and senior dogs, and it is painful even when dogs keep eating (AVDC). A daily routine is the practical lever owners control at home.
Is my data stored?
Your answers stay in your browser (localStorage) so you can restore your last session. No account, no personal data, nothing sent to a server.
Sources
1. Kealy RD et al. "Effects of diet restriction on life span and age-related changes in dogs." JAVMA, 2002. (S4 slot — verified citation pending) ·
2. AAHA Canine Life Stage Guidelines, 2019. ·
3. AVDC — Periodontal Disease, owner resources. ·
4. WSAVA Global Nutrition Toolkit.
Full citation audit tracked in Methodology §S4.