Convert your pet’s age to human years. This free pet age calculator covers dogs by size, cats and rabbits, showing the human-equivalent age and life stage for a more accurate picture than the old x7 rule.
Choose your pet (dogs are split by size, since larger dogs age faster) and enter their age in years. You can use decimals, like 0.5 for six months.
Pets don’t age at a steady “7 years per year” — the first couple of years count for much more, then the rate settles. These are estimates; large dogs age faster than small ones, and breed and health matter too.
What This Pet Age Calculator Does
A pet age calculator estimates your pet’s human-equivalent age. The old “multiply by 7” rule is too simple — pets age fast in their first two years, then more slowly, and larger dogs age quicker than small ones.
How Pet Years Convert to Human Years
Dogs/cats: year 1 = 15, year 2 = +9 (24 total)Then per year: small dog +4, medium +5, large +6, cat +4
So a 5-year-old medium dog is about 39 human years, a large dog about 42, and a 5-year-old cat about 36.
Pet Age at a Glance
| Pet age | Medium dog | Cat |
|---|---|---|
| 1 year | 15 | 15 |
| 2 years | 24 | 24 |
| 5 years | 39 | 36 |
| 10 years | 64 | 56 |
Why Size and Species Matter
Small dogs often live longer and age more slowly than large breeds, so a giant breed at 8 is “older” in human terms than a toy breed at 8. Cats tend to age slightly slower than dogs after the first two years, and rabbits follow their own, shorter timeline.
How to Use the Pet Age Calculator
- Choose your pet — dog by size, cat or rabbit.
- Enter their age in years (decimals are fine).
- Read the human-equivalent age and life stage.
Looking for a dog- or cat-specific breakdown? See our Dog Age Calculator or Cat Age Calculator.
Using the Pet Age Calculator to Plan Your Pet’s Care
The most practical use of a pet age calculator is spotting when your pet is moving into a new life stage, because care needs shift at those points.
- Senior years: vets commonly suggest more frequent check-ups for older pets, since dental disease, arthritis and kidney changes become more common with age.
- Diet: foods are labelled for growth, adult maintenance or senior pets, and a pet age calculator helps you judge when a switch is worth discussing with your vet.
If you do not know your pet’s birthday, as with many rescue animals, a vet can estimate age from the teeth, eyes and coat. Enter that estimate into the pet age calculator and treat the result as approximate.
Remember that a pet age calculator gives an average for the species and, for dogs, the size group. For background on why larger dogs tend to have shorter lives, see the aging in dogs article on Wikipedia, then use your pet age calculator result as a starting point for a conversation with your vet.