Pet age calculator

How old is your pet in human years?

Your dog's or cat's age in human years from today's science, not the old ×7 rule, plus its life stage.

Pet

Years

Months

Dog size

Age in human years

53 years

At 4 years, your dog is about as old as a 53-year-old person.

Life stage

Stage now: Mature adult
Next stage: Senior from 9 years, 5 months
The old ×7 rule says: 28 years

Wang et al., Cell Systems 2020; AAHA Canine Life Stage Guidelines 2019; McMillan et al., Scientific Reports 2024

An estimate: the formula comes from Labradors, and breeds and individual dogs age differently.

Dog years to human years

Dogs age fast in their first year and slower after it: a 1-year-old is like a 31-year-old person, but each later year adds less, unlike the straight ×7 line.

Dog's age in human years
Old ×7 rule

Dog years to human years
Dog's age	Human years	Old ×7 rule
1 year	31 years	7 years
2 years	42 years	14 years
3 years	49 years	21 years
4 years	53 years	28 years
5 years	57 years	35 years
6 years	60 years	42 years
7 years	62 years	49 years
8 years	64 years	56 years
9 years	66 years	63 years
10 years	68 years	70 years
11 years	69 years	77 years
12 years	71 years	84 years
13 years	72 years	91 years
14 years	73 years	98 years
15 years	74 years	105 years
16 years	75 years	112 years

Your dog's or cat's age in human years from today's science, not the old ×7 rule, plus its life stage.

How to use

Choose dog or cat.
Enter your pet's age in years and months. For a dog, pick its size too: small, medium or large.
Read the age in human years and the life stage. The chart shows the whole curve next to the old ×7 line.

Pet ages compared with human years

Pet age (years)	Dog	Cat
1	31	15
2	42	24
4	53	32
7	62	44
10	68	56
15	74	76

How it works

Dogs and cats don't age at a steady speed. They race through childhood in their first year or two and then slow down. That's why "one dog year is seven human years" goes wrong: it makes a 1-year-old dog seven, when by the science it is more like a young adult of about 31.

For dogs, the calculator uses a 2020 study from the University of California San Diego (Wang et al., Cell Systems). The team compared age-related changes in the DNA of 104 Labradors with those of people and found: human age = 16 × ln(dog age) + 31, where ln is the natural logarithm and the dog's age is in years. Example: a 4-year-old dog gives 16 × ln 4 + 31 = 16 × 1.386 + 31 ≈ 53 human years.

For cats, the calculator follows the Feline Veterinary Medical Association's chart: a 1-year-old cat is like a 15-year-old person, a 2-year-old like 24, and each later year adds 4, so a 10-year-old cat is about 56. Life stages come from vets' guidelines (AAHA/AAFP for cats, AAHA for dogs). Small dogs live longer than large ones (a median of 12.7 against 11.9 years in a UK study), so large dogs turn senior earlier.

These are friendly estimates, not a health check. The dog formula comes from one breed, Labradors, and the researchers note that breeds with much shorter or longer lives may follow a different curve. Your vet can tell how your own pet is doing.

Frequently asked questions

Is one dog year really seven human years?

No. Dogs grow up much faster than that at first: a 1-year-old dog is roughly like a 31-year-old person. After that, each year adds fewer human years, so ×7 is too low for young dogs and too high for old ones.

Why does my dog's size matter?

Smaller dogs tend to live longer than bigger ones. Vets count a dog as senior in the last quarter of its expected life, so a large dog reaches the senior stage about half a year earlier than a small one.

My dog is a mix. Which size should I pick?

Pick the size closest to your dog's adult size. The human-age number stays the same; only the life stages move a little.

When is a cat a senior?

Vets count cats over 10 years old as seniors, about 56 or more in human years.

Why is there no human age for a newborn?

The comparison starts at two months for dogs and one month for cats. Earlier ages are outside the method used here.

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