Dog age calculator: dog years to human years

Enter your dog’s age or date of birth and its size. You get the age in human years from the American Kennel Club chart, a DNA-based formula for comparison, and the life stage as AAHA defines it.

Calculate your dog’s age

[data-age-form]{display:none!important}[data-age-grid]{display:block!important;max-width:36rem}The calculator needs JavaScript. Below is the result for a 7-year-old medium-sized dog; the full chart is further down the page.

7 years · Medium, 21–50 lb

In human years

≈ 47

AKC chart for medium dogs

Life stage (AAHA)

Mature adult

From maturity until the last 25% of the expected lifespan. Medium dogs live 10 to 13 years on average (AKC), so their senior stage starts between 7½ and 9¾ years.

DNA-based formula

≈ 62

Wang et al., 2020. Built on 104 Labradors; size is not taken into account.

At any stage, ask your vet how often your dog should come in for a checkup. AAHA on life stages (opens in a new tab)

Human years are a rough comparison, not a medical measure. Everything is calculated in your browser; nothing is sent anywhere.

How the calculator works

Human years: the AKC chart

The main number comes from the American Kennel Club chart “How old is my dog in human years?”. It has four columns by adult weight: small, medium, large and giant. AKC also quotes the American Veterinary Medical Association’s rule of thumb: the first year of a medium-sized dog equals about 15 human years, the second about 9 more, and each year after that about 5.

The chart lists whole years from 1 to 16. Between birthdays the calculator draws a straight line from one row to the next; under 1 year or over 16 it shows “under” or “over” the nearest row instead of guessing.

For comparison: the DNA-based formula

In 2020, a UC San Diego team compared age-related marks on DNA (methylation) in dogs and people. Their formula is human age = 16 × ln(dog age) + 31, with ln the natural logarithm: a 1-year-old dog comes out at about 31, a 4-year-old at 53, a 12-year-old at 71.

The study used 104 Labrador retrievers, and the authors note that breeds with very different lifespans may need a different formula. It ignores size: read it as a second opinion.

Life stage: the AAHA guidelines

The 2019 AAHA Canine Life Stage Guidelines name four stages: puppy (until rapid growth ends, about 6 to 9 months), young adult (until maturity, by 3 to 4 years), mature adult, and senior, the last 25% of the expected lifespan. AAHA sets no fixed age for the last two, because lifespan depends on breed and size.

To place the senior stage, the calculator uses AKC’s average lifespans by size, a resource the guidelines list. The fifth stage, end of life, isn’t tied to age and isn’t shown.

Dog age chart: dog years to human years

The full AKC chart, by your dog’s size as an adult.

Dog age in human years by size. Source: American Kennel Club.
Dog’s age	Smallup to 20 lb	Medium21–50 lb	Large51–100 lb	Giantover 100 lb
1 year	15	15	15	12
2 years	24	24	24	22
3 years	28	28	28	31
4 years	32	32	32	38
5 years	36	36	36	45
6 years	40	42	45	49
7 years	44	47	50	56
8 years	48	51	55	64
9 years	52	56	61	71
10 years	56	60	66	79
11 years	60	65	72	86
12 years	64	69	77	93
13 years	68	74	82	100
14 years	72	78	88	107
15 years	76	83	93	114
16 years	80	87	99	121

Why “multiply by 7” is wrong

The seven-year rule dates back to at least the 1950s, but dogs don’t age at a steady rate. They grow up fast: the AKC chart counts the first year as 15 human years (12 for giant dogs). Later a small dog adds about 4 a year and a giant dog 7 or 8, so a 10-year-old is 56 or 79, not 70.

The DNA study came to the same conclusion from another direction: a 1-year-old dog compares with a 30-year-old person, not a 7-year-old. And the AAHA guidelines suggest defining a dog’s life stage by age and characteristics rather than calculating human-age equivalents at all.

Frequently asked questions

How old is a 1-year-old dog in human years?

By the AKC chart, 15 for small, medium and large dogs and 12 for giant dogs. The DNA-based formula gives about 31: a different method, a different number.

When is a dog considered a senior?

AAHA defines it as the last 25% of the expected lifespan, so it depends on breed and size. With AKC’s average lifespans, that is from 6 to 7½ years for giant dogs and from 7½ to 11¼ for small ones. Your vet can estimate it for your dog.

Does the calculator save or send what I enter?

No. It runs in your browser, nothing is sent anywhere, and nothing is stored: reload the page and it starts over.

Sources

American Kennel Club. How to Calculate Dog Years to Human Years (chart “How old is my dog in human years?”). 2026. akc.org (opens in a new tab) (accessed October 16, 2026)
Cell Systems. Wang T. et al. Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome. 2020. doi.org (opens in a new tab) (accessed October 16, 2026)
UC San Diego Today. How Old Is Your Dog in Human Years? Scientists Develop Better Method than ‘Multiply by 7’. 2020. today.ucsd.edu (opens in a new tab) (accessed October 16, 2026)
American Animal Hospital Association. 2019 AAHA Canine Life Stage Guidelines: Canine Life Stage Definitions. 2019. aaha.org (opens in a new tab) (accessed October 16, 2026)
American Animal Hospital Association. 8 Things You Need To Know About AAHA’s Canine Life Stage Guidelines. 2019. aaha.org (opens in a new tab) (accessed October 16, 2026)
American Kennel Club. How Long Do Dogs Live?. 2021. akc.org (opens in a new tab) (accessed October 16, 2026)