About Dog Years

A small, independent tool built to answer one question properly: how old is your dog, really, in human terms?

Dog Years (dogyears.info) started from a simple frustration: most "dog years" calculators online still use the old ×7 rule of thumb — a 1950s guess that doesn't hold up to how dogs actually age. A Great Dane and a Chihuahua do not age at the same rate, and neither ages in a straight line through its life.

This site uses The Royal Kennel Club's published guidance instead, which accounts for a dog's size and breed. The first two years of a dog's life pack in far more ageing than any later year — a one-year-old dog is already roughly the human equivalent of a 15-year-old — and after that, the pace of ageing depends heavily on adult size. Small breeds tend to age more slowly in their later years than giant breeds.

How the calculator works

You can look up your dog's size either by breed (using The Royal Kennel Club's official size classifications, covering over 225 recognised breeds) or by entering an approximate adult weight if your dog is a crossbreed or not listed. The calculator then applies The Royal Kennel Club's size-adjusted ageing data — a genuine lookup table rather than a single formula, since real ageing data isn't a clean multiplication sum.

We've also kept the classic ×7 rule available as a toggle, purely for comparison — it's still what most people have heard of, even though it's the less accurate of the two.

Who's behind this

Dog Years started as a way to settle a question my daughter kept asking: how old is Saxon, our German Shepherd, really, in human years? Once we'd worked it out properly — using real size-adjusted data rather than the old ×7 rule — it seemed a shame to keep it to ourselves, so with her blessing we tidied it up and shared it with the world. Several of the site's nicest touches were her idea too, including the birthday email reminder, so you never miss finding out how much older your dog has become.

Dog Years is run independently as a small side project — not by a veterinary organisation, and not affiliated with The Royal Kennel Club itself. All breed and ageing data is sourced from their publicly published guidance, credited throughout the site.

A note on accuracy

The figures on this site are estimates based on published breed and size averages. Individual dogs vary with genetics, health, neutering status and lifestyle. This tool is meant to be a fun, informative guide — not a substitute for advice from your vet, particularly if you have concerns about your dog's health or ageing.

Some links on this site are affiliate links, meaning we may earn a small commission if you make a purchase through them, at no extra cost to you. See our Privacy Policy for more detail.