How old is my dog in human years?

Roughly 15 human years at age 1 and 24 at age 2 for most dogs. After that, small dogs add about 4 human years a year and large and giant breeds add more, so a 10-year-old dog is about 56 if it is small but about 66 if it is large, on the AKC chart. Enter your dog’s age and size above for the exact figure.

Is one dog year really seven human years?

No. The American Veterinary Medical Association says plainly that dogs do not age at a rate of seven human years for each dog year. Dogs grow up much faster than that in their first two years, then age more slowly, and big breeds age faster than small ones later in life.

Why do large dogs age faster than small dogs?

Large and giant breeds have shorter life expectancies, so they reach old age sooner even though they grow up at a similar pace. That is why the size columns of the chart are the same for the first five years and then pull apart. The biology behind it is still being studied.

Which is more accurate, the size chart or the DNA formula?

Neither is a measurement of your dog. The size chart reflects veterinary rules of thumb and accounts for size. The DNA methylation formula is grounded in measured molecular changes, but it was built from a single breed, Labrador retrievers, so it ignores size. For a Labrador or similar dog, it is interesting to compare the two.

When is my dog a senior?

AAHA’s 2019 guidelines define a senior dog as one in the last 25% of its estimated lifespan, so it depends on breed and size. Enter an expected lifespan to use that rule. Without one, the calculator uses the AVMA’s rule of thumb: small dogs are generally considered senior at about 7, larger breeds at 5 to 6.

Which size should I pick for a puppy or a mixed breed?

Use the weight your dog is expected to reach as an adult, not its current weight. Your veterinarian can estimate adult size for a puppy or a mixed breed. If you are converting from kilograms, see kilograms to pounds.

Dog Age Calculator — Dog Years to Human Years by Size

Enter your dog’s age and size to see its age in human years on the AKC size chart and the 2020 DNA-methylation formula side by side, plus its life stage.

How to use the dog age calculator

Enter your dog’s age in years and months — for a puppy, you can type the whole age in months with 0 years — and pick the size class that matches its adult weight. The calculator shows the human-equivalent age from the American Kennel Club’s size chart, the result of the 2020 DNA-methylation formula from UC San Diego, the old “× 7” figure for comparison, and your dog’s life stage. Until you type, the example shows an 8-year-old large dog such as a Labrador. Your inputs are kept in the page address, so you can share the result.

Why “multiply by 7” is a myth

The seven-to-one rule assumes dogs age at the same steady pace all their lives. They do not. A one-year-old dog is usually close to adult size and able to have puppies, which makes it more like a teenager than a seven-year-old child. After the first two years the pace slows, and it then depends on size: large and giant breeds live shorter lives, so they reach old age sooner. The AVMA states outright that dogs do not age seven human years per calendar year. The rule gets both ends wrong: at age 1 it says 7 instead of about 15, and at 16 it says 112 for a small dog that the chart puts at 80.

The size chart

The AKC’s rule of thumb is that the first year of a medium-sized dog’s life equals about 15 human years, the second adds about 9, and each year after that adds about 5. Its chart splits this by size. Between chart ages the calculator interpolates in a straight line; under 1 year it runs from birth through 10 human years at 6 months, the figure on AAHA’s age chart; past 16 it extends each column at its average rate over ages 11–16 and says so.

Dog age in human years by size (AKC)
Dog age	Small20 lb or less	Medium21–50 lb	Large51–100 lb	Giantover 100 lb
1	15	15	15	12
2	24	24	24	22
3	28	28	28	31
4	32	32	32	38
5	36	36	36	45
6	40	42	45	49
7	44	47	50	56
8	48	51	55	64
9	52	56	61	71
10	56	60	66	79
11	60	65	72	86
12	64	69	77	93
13	68	74	82	100
14	72	78	88	107
15	76	83	93	114
16	80	87	99	121

Notice that small, medium and large dogs match for the first five years, and giant breeds start lower at age 1 but then age fastest. The chart is a practical summary of veterinary experience, not a precise biological measurement.

The DNA methylation formula

human age = 16 × ln(dog age) + 31

In 2020 researchers led by Tina Wang and Trey Ideker at the University of California San Diego measured chemical marks on DNA (methylation) that change with age in 104 Labrador retrievers aged 4 weeks to 16 years, and matched them to the same changes in people. The result, published in Cell Systems, is a logarithmic curve: dogs age very fast early on and much more slowly later. “ln” is the natural logarithm, so a 1-year-old dog comes out at 31, a 2-year-old at 42.1 and a 10-year-old at 67.8. The curve rises so steeply in the first months that it gives nonsensical values for young puppies, so the calculator shows it from age 1. It came from a single breed, so it does not account for size.

Worked example

An 8-year-old Labrador retriever (a large dog, 51–100 lb):

Size chart: the large-dog column reads 55 human years at age 8.
DNA formula: 16 × ln(8) + 31 = 16 × 2.079 + 31 = 64.3, about 64.
The “× 7” rule would say 8 × 7 = 56.
Life stage: Senior. Larger breeds are often considered senior at 5 to 6 (AVMA). If you enter a 12-year expected lifespan, the AAHA rule puts the senior stage at 9 instead, so the calculator shows “Mature adult”.

Life stages

The American Animal Hospital Association’s 2019 Canine Life Stage Guidelines divide a dog’s life into five stages:

Puppy: birth until rapid growth stops, at about 6 to 9 months depending on breed and size.
Young adult: from the end of rapid growth until physical and social maturity at about 3 to 4 years.
Mature adult: from maturity until the last 25% of the estimated lifespan.
Senior: the last 25% of the estimated lifespan.
End of life: a stage defined by health, not age, which can come at any point.

AAHA deliberately does not give fixed ages for the mature adult and senior stages, because lifespans vary so much by breed and size. That is why the calculator asks for an expected lifespan, and falls back on the AVMA’s simpler guidance when you leave it blank. Each stage has different care priorities, from vaccines and training for puppies to earlier screening for age-related disease in seniors, so it is worth asking your veterinarian which stage your dog is in. For cats, use the cat age calculator; to count your dog’s exact age in days from a birth or adoption date, try the age calculator.

Last reviewed 25 September 2026 · Built and checked by the Reeliy team · How we test our tools

Dog Age Calculator

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