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LifeQnA

PETS · CALCULATOR

Dog and Cat Age Calculator

Enter your pet’s age to see roughly how old it is in human years and which life stage it is in.

Convert your pet’s age

Pet
Size

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Pet age chart

Human years (rounded)
Pet ageDog (medium)Cat
1 year1515
2 years2424
3 years2928
5 years3936
7 years4944
10 years6456
12 years7464
15 years8976

How pet years are counted

Choose dog or cat, pick your dog’s size, and enter the age in years and months. The first year counts as about 15 human years and the second as about 9 more. After that, each year adds about 5 for dogs and 4 for cats.

Why size matters for dogs

Large and giant breeds have shorter lives and reach their senior years earlier than small dogs, so a 6-year-old Great Dane and a 6-year-old Chihuahua are at different stages. Use the result as a starting point for a conversation with your vet.

Frequently asked questions

Is one dog year really seven human years?

No. Dogs mature much faster at first: veterinary guidance puts a 1-year-old dog at about 15 human years and a 2-year-old at about 24, then about 5 years for each year after that for a medium-sized dog.

How old is my cat in human years?

Under the 2021 AAHA/AAFP guidelines’ widely used conversion, a 1-year-old cat is about 15, a 2-year-old about 24, and each year after that adds about 4 human years. A 10-year-old cat is about 56.

When is a dog a senior?

Small and medium dogs are usually considered senior from about 7, and large dogs from about 5 to 6, because bigger breeds age faster.

What is the DNA-based dog age formula?

A 2020 study of Labrador retrievers compared chemical changes in DNA with humans and proposed human age = 16 × ln(dog age) + 31. It ages young dogs very quickly and is only meaningful from age 1.

Sources and last updated

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