Dog Age Calculator
Estimate a dog's age in human-equivalent years, allowing for its size.
Beyond multiply-by-seven
The old rule that one dog year equals seven human years is a myth that does not hold up. Dogs mature very fast in their first couple of years and then age more gradually, and size matters a lot — small breeds live longer and age more slowly than large ones. This estimates a more realistic human-equivalent age accounting for that.
Enter your dog's age and size for a better estimate.
Why size changes the maths
The genuinely interesting fact is that larger dogs age faster and have shorter lifespans, which is unusual in the animal world — bigger usually means longer-lived. A small dog might be sprightly at twelve while a giant breed is elderly by then. A dog also reaches the equivalent of adulthood remarkably quickly, packing a lot of ageing into that first year or two before the pace settles. So a single multiplier can never be right.
Questions & answers
Is one dog year really seven human years?
No — that is a myth. Dogs age fast early, then more slowly, and size matters: small breeds age slower than large ones.
Why do big dogs age faster?
Larger breeds have shorter lifespans and age more quickly, unusually for animals, so a giant breed is elderly younger than a small one.
Is anything uploaded?
No. The estimate happens in your browser.