Dog and Cat Age Calculator
Work out what your dog's or cat's age comes to in human years.
Daily LifeResult
Human age equivalent
39 years old
How is it calculated?
Enter the species (dog or cat), the size if it's a dog, and the age. The tool counts the first year as 15, the second as 9 more (24 total), and every year after that at a fixed rate that depends on species and size. This is a commonly used veterinary approximation, not an exact per-breed table.
Formula
Year 1: 15 × age Year 2: 15 + 9 × (age − 1) After that: 24 + (yearly rate) × (age − 2)
Example
Species: Dog · Size: Medium (10–25 kg / 22–55 lb) · Age: 5 → Human age equivalent: 39 years old
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Frequently asked questions
How accurate is this?
It's a widely used veterinary approximation, not an exact per-breed table. Ask your vet about your pet's actual health and life stage.
Why does size matter for dogs?
Larger breeds reach adulthood sooner but age faster afterwards; smaller breeds age more slowly and steadily, similar to cats.
Why isn't there a size option for cats?
The size difference between cat breeds isn't as large as between dog breeds and doesn't affect the aging rate the same way, so every cat uses the same formula.
Does this work for a young pet?
Yes, ages under 1 year are scaled proportionally too — a 6-month-old kitten or puppy comes to 7.5 human years.