How old is my pet in human years?
For dogs, a 2020 study compared the way DNA changes with age in dogs and in people and gave a formula: human age ≈ 16 × ln(dog age) + 31, where ln is the natural logarithm. A 1-year-old dog comes out at about 31, a 4-year-old at about 53, a 10-year-old at about 68 and a 15-year-old at about 74. For cats, the usual chart from the AAFP–AAHA Feline Life Stage Guidelines counts the first year as 15 human years, the second as 24 in total, then 4 for every year after: a 10-year-old cat is about 56.
This page asks first. Pick cat or dog, slide its age, and a candle lights on the rim of a birthday cake for each year. Then guess its human age on a ring of beads, one for every human year, before the real number turns the right beads red. Two more questions follow: whether the old “times seven” rule is too high or too low, and either your cat’s life stage (kitten, young adult, mature adult or senior) or a puppy milestone.
Both conversions are rough. The dog formula comes from Labrador retrievers, and breeds age at different speeds: large dogs tend to age faster and small dogs live longer. The cat chart is a rule of thumb rather than a measurement. Your pet’s vet is the best guide to how it is actually ageing.
What it asks
Five quick questions.
The questions
- Cat or dog
- Its age in years, with a candle lit for each one
- Your guess at its human age, on a ring of beads
- Whether “times seven” is too high, too low, or both
- Cats: its life stage. Dogs: a puppy milestone
Your result
- Your pet’s human age and a label for its stage of life
- A table of cat or dog years to human years
- How the number is worked out
- A share card with its human age, real age and what “times seven” would have said
Pet years: common questions
Is this test free? Do I need to sign up to see my result?
Yes, it’s free, and there’s nothing to sign up for: no account, no email, no payment. Your result appears on this page the moment you finish, and you can share it or play again straight away.
Are my answers saved or sent anywhere?
No. Your answers and your result stay in your browser: nothing you pick or type is sent to us. The live site counts anonymous visits (that a test was opened, how far people got, whether they finished) without any of the answers. Your latest result is kept in this browser so you can find it again, and a challenge link carries only the name of your result. If you add a photo of your pet to the share card, it is drawn on your device and never uploaded.
How long does it take, and can I play on my phone?
About one minute. It works on a phone, tablet or computer in any up-to-date browser, as long as 3D graphics (WebGL) are switched on, which they are almost everywhere. Sound effects are optional: the switch is in the top corner.
What does the pet age calculator tell me?
The calculator gives your cat’s or dog’s age in human years and a label for that age, from Teen Spirit (under 25) through Young Professional, Midlife Mellow and Golden Years to Wise Elder (80 and over). Cats also get their life stage from vets’ guidelines. The result sheet has a year-by-year table and checks your guesses. The share card shows the human age on a badge with the real age, the “times seven” figure and the age at the next birthday, with your pet’s photo if you add one, and a challenge link sends the test to a friend.
How is my pet’s human age worked out, and how accurate is it?
For dogs, the calculator uses the formula from Wang and colleagues’ 2020 study in Cell Systems: human age ≈ 16 × ln(dog age) + 31, built from DNA changes in 104 Labrador retrievers. Cats have no such formula, so it uses the chart published with the 2010 AAFP–AAHA Feline Life Stage Guidelines: 15 for the first year, 24 by the second, then 4 a year. Ages are in whole years. Both are rough translations, not a medical age: breed, size and health change how a pet actually ages.
Is one dog year really seven human years?
No. Cats and dogs age fastest in their first year or two and much more slowly after, so no single multiplier fits. By the 2020 DNA formula, a 1-year-old dog is already about 31 in human terms. “Times seven” is off at both ends of a pet’s life, and the calculator shows where the two methods cross for your own cat or dog.
How old is a cat in human years?
By the usual chart, a cat’s first year counts as 15 human years, its second brings it to 24, and every year after adds 4. So a 5-year-old cat is about 36, a 12-year-old about 64 and an 18-year-old about 88. Vets’ guidelines also sort cats into life stages: kitten up to 1 year, young adult 1–6, mature adult 7–10 and senior over 10.
Where the numbers come from
The dog formula and the cat chart are from the sources below. Cat life stages follow the AAHA/AAFP guidelines: kitten to 1 year, young adult 1–6, mature adult 7–10, senior over 10.
How the numbers are worked out
Dogs
Human age = 16 × ln(dog age) + 31, rounded, from Wang et al. (2020), who matched age-related changes in the DNA of Labrador retrievers and people.
Cats
15 at one year, 24 at two, then 4 more for each year, from the chart published with the 2010 AAFP–AAHA Feline Life Stage Guidelines.
Your guess
Within 6 years of the real human age counts as right.
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