About Whiskerclock
How old is your pet, really?
Why this exists
Almost everyone has heard that one dog year equals seven human years. It's a tidy rule, it's easy to remember, and it's wrong. It was never based on research — the most common explanation is that someone in the mid-twentieth century divided average human lifespan by average dog lifespan and the number stuck.
The reality is more interesting. Dogs and cats do not age at a constant rate. They age enormously fast in their first year, quickly in their second, and then far more slowly for the rest of their lives. A one-year-old dog is not a seven-year-old child; developmentally it is closer to a teenager. Whiskerclock exists to give you a number that reflects that curve instead of flattening it.
Where the numbers come from
For dogs, we use a logarithmic curve derived from research at the University of California, San Diego, which compared DNA methylation — chemical marks on DNA that accumulate predictably with age — in Labrador Retrievers and humans. This "epigenetic clock" approach produces a much better fit to biological reality than any straight multiplication, and it is where the name of this site comes from.
For cats, we use the staged approach that veterinary bodies broadly agree on: roughly 15 human years for the first year, about 9 more for the second, and approximately 4 per year after that.
The exact formulas are published in full on the calculator page. We would rather show our working than ask you to trust a black box.
How accurate is it?
Honestly: it is a well-grounded estimate, not a diagnosis. Every formula of this kind describes a population average, and your pet is an individual. The biggest single factor we do not yet account for is size — a Great Dane and a Chihuahua age at genuinely different rates, and by eight years old they are in quite different stages of life. Breed-size adjustment is the next feature we plan to add.
Whiskerclock is for curiosity and fun. If you are worried about your pet's health or want to know what care their age calls for, your vet knows your animal and we do not.
How the site is built
Whiskerclock is a deliberately small, fast, static website. There are no accounts, no tracking of what you enter, and no database — the calculation runs entirely in your browser. Our privacy policy explains the details, including how advertising cookies work.
Get in touch
Corrections, suggestions, and pet photos are all welcome at hello@whiskerclock.com.