The “one pet year equals seven human years” myth
This simple rule is wrong. Dogs and cats become adults in barely one to two years, then age more slowly. One early year of life is worth far more than seven human years, while a year late in life is worth less.
How age in human years is calculated
The first year is worth about 15 human years, the second adds 9 (24 by age two), then each following year adds a few human years. For dogs, that pace depends on size: large breeds age faster than small ones.
The main life stages
Understanding your pet's life stage helps you adapt its diet, activity and health care.
Puppy
Fast growth: vaccines, deworming, socialisation and identification (microchip) are the priorities of the first months.
Adult
Prime years: one vet visit a year, a suitable diet and regular activity are enough to keep them healthy.
Senior
Watch weight, teeth and joints. Two vet visits a year help catch health issues early.
An estimate, not a diagnosis
This calculator gives a ballpark figure. Every animal ages at its own pace, and only a vet can properly assess its health.
Our sources
- Main method (first year ≈ 15 human years, then progression by size): the American Kennel Club's conversion reference. akc.org
- Cat life stages: the AAHA / AAFP feline life-stage guidelines. catvets.com
- DNA method (dog): Wang et al., “Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome”, Cell Systems, 2020 (formula 16 × ln(age) + 31, derived from Labradors). cell.com
- Life expectancy by size: veterinary reviews. santevet.com
Going further
Welcoming an animal well also means planning ahead and being ready to react.
FAQ - Frequently asked questions
Why does my dog's size change the result?
The bigger the dog, the faster it ages. A small dog can live 15 years or more, while a giant breed often reaches its senior years by age 6 or 7. That's why we ask for size.
When is my dog considered senior?
It depends on size: around 10 for a small dog, but as early as 6 or 7 for a large or giant one. From then on, more regular vet check-ups are recommended.
Does this replace the vet?
No. It's an estimate to help you understand your dog's life stage. Only a vet can properly assess its health and true age.