Dog and Cat Age Calculator

Convert your dog's or cat's age into human years. This dog age calculator uses a size-based chart and a DNA-based formula, and cats follow the common veterinary rule.

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Pet

Decimals work: 1.5 = 18 months

Age in human years
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How to use the Dog and Cat Age Calculator

  1. Choose Dog or Cat.
  2. Enter your pet's Age in years, and for a dog pick its size.
  3. Press Calculate. The human-year age appears, with the other methods for comparison.

How it works

dog, epigenetic: human age = 16 × ln(dog age) + 31
dog, size chart: read from the table, with straight lines between years
cat: 15 at 1 year, 24 at 2, then + 4 each year

The epigenetic formula comes from a 2019 University of California San Diego study of DNA changes in Labrador retrievers. The size chart reflects that large dogs age faster after about five years.

Examples

  • A 10-year-old dog is about 68 human years by the epigenetic formula.
  • By the size chart, a 10-year-old small dog is 56, and a giant breed 79.
  • A 10-year-old cat is 56 in human years.

Why the 7-year rule is wrong

Dogs and cats grow up very fast, then age more slowly. A 1-year-old dog is more like a 15-year-old teenager than a 7-year-old child. After that, each year counts for about 4 to 9 human years depending on size.

Limitations

  • All methods are estimates. Breed, health, and lifestyle matter a lot.
  • The epigenetic formula is not meant for dogs under 1 year.

Frequently asked questions

How old is my dog in human years?

Enter the age and size. A 10-year-old medium dog is about 60 by the chart and 68 by the epigenetic formula.

Is 1 dog year 7 human years?

No. The first year is closer to 15 human years, and later years depend on size.

How old is a 10-year-old cat in human years?

About 56.

Often used together with the Dog and Cat Age Calculator.

  • Age Calculator

    Gives an exact age in years, months, and days from a date of birth.

  • Date Calculator

    Adds or subtracts a period from a date to give a new date.