How dog years actually work
The old saying — one dog year is seven human years — is the sort of thing that's stuck around because it's easy to remember, not because it's true. Dogs do most of their ageing in their first two years: a one-year-old Labrador is already physically mature, roughly the equivalent of a fifteen-year-old human. By two, they're closer to a young adult. After that, the rate slows down — and it slows down by different amounts depending on how big they are.
Small dogs live longer
It's one of the quiet cruelties of dog ownership: the bigger the dog, the shorter the average lifespan. A toy or small breed can often see their mid-teens, while a giant breed like a Great Dane averages closer to seven or eight years. The calculator above accounts for this by ageing larger dogs faster after year two — so a ten-year-old Great Dane lands in the same human-equivalent ballpark as a much older small dog.
Life stages, not just numbers
Vets tend to think about dogs in stages — Puppy, Pup, Adult, Mature, Senior, Veteran — because the relevant questions change across each one. Puppies need vaccination schedules and socialisation; adults need exercise and weight control; seniors often need more frequent check-ups and joint support. The human-years number is a nice headline, but the stage is usually the more useful answer.
Make this one count
However many human years your dog turns out to be, none of them come back. If you've been meaning to get them painted, this is probably your sign — upload a photo and we'll turn it into something worth hanging on a wall.
Frequently asked questions
Why does my dog's size change their human age?
Smaller dogs tend to live longer and age more slowly past puberty; giant breeds age faster. The calculator uses a size-aware variant of the AVMA's curve so a ten-year-old Chihuahua and a ten-year-old Great Dane aren't given the same human-equivalent age — because vets don't treat them as if they were.
How accurate is the dog-to-human age calculation?
It's a sensible rule of thumb, not a medical assessment. The old 'one dog year equals seven human years' is too blunt, so we use a sliding curve: dogs mature very quickly in their first two years, then age at a steadier, size-dependent rate. Individual health and breed history varies — talk to your vet for anything clinical.
What counts as a toy, small, medium, large or giant dog?
Toy is under 4 kg (Chihuahua, Pomeranian). Small is 4–9 kg (Jack Russell, Miniature Dachshund). Medium is 9–23 kg (Cocker Spaniel, Beagle). Large is 23–40 kg (Labrador, Boxer). Giant is over 40 kg (Great Dane, St Bernard). If you're not sure, pick the closest — being one band out only shifts the result by a year or two.
What do the life stages mean?
Puppy (0–1), Pup (1–2), Adult (2–7), Mature (7–10), Senior (10–13), and Veteran (13+). These are the stages most UK vets use when talking about behaviour, feeding and check-up frequency — a more useful frame than a single number.
Do you store anything I enter here?
No. The calculator runs entirely in your browser — your dog's age and size never leave the page. There's no account needed and nothing is sent anywhere.
Can I turn my dog's photo into a portrait?
Yes — that's what we do. Upload a photo and we'll paint your dog in the style of your choice, from oil and watercolour to pop and renaissance. Prints, framed canvases and posters from £29.