Dog age chart by size: small, medium, large and giant dogs
A 7-year-old dog is 44 in human years if it weighs 20 lb or less, 47 at 21-50 lb, 50 at 51-100 lb and 56 over 100 lb, because big dogs age faster once they are grown. This is the American Kennel Club chart for the four sizes, years 1 to 16, as a table you can read rather than an image, with the weight cut-offs in kilograms, the 15/9/5 rule next to it so you can see where they disagree, and the age at which each size counts as a senior.
Dog age chart by size, years 1 to 16
Human years for each dog year, by the size of the adult dog. Small is 20 lb (9 kg) or less, medium 21-50 lb (up to 23 kg), large 51-100 lb (up to 45 kg), giant over 100 lb. For ages between the rows, the dog age calculator takes years and months.
| Dog years | Small (20 lb or less) | Medium (21-50 lb) | Large (51-100 lb) | Giant (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 |
Which size class is my dog?
Go by healthy adult weight. Small: Chihuahua, Pug, Shih Tzu, Cavalier King Charles Spaniel. Medium: Beagle, Cocker Spaniel, French Bulldog, most Border Collies. Large: Labrador and Golden Retrievers, German Shepherds, Boxers. Giant: Great Danes, and the heavier Rottweilers and Bernese Mountain Dogs. A dog on the boundary reads the heavier column; an overweight dog reads the column for the weight it should be. Breed weights are in how much to feed a dog by breed.
Size chart against the 15/9/5 rule: where they disagree
The rule of thumb (15 human years for the first dog year, 9 for the second, 5 for each year after) is what most dog years to human years charts print, and what the calculator on this site calls the AKC rule. The size chart is a different object: a table the AKC publishes with a column per size, and its medium column is not the rule. Both are shown so the gap is visible instead of argued about.
| Dog years | 15/9/5 rule | Chart, medium | Difference | Epigenetic clock |
|---|---|---|---|---|
| 2 | 24 | 24 | 0 | 42 |
| 4 | 34 | 32 | -2 | 53 |
| 7 | 49 | 47 | -2 | 62 |
| 10 | 64 | 60 | -4 | 68 |
| 13 | 79 | 74 | -5 | 72 |
| 16 | 94 | 87 | -7 | 75 |
Where the epigenetic clock lands
The clock (human age = 16 x ln(dog age) + 31, UC San Diego) reads DNA methylation rather than lifespan statistics. It was measured in Labradors, runs far ahead of both tables for young dogs and converges in old age, and is here for comparison, not as the default.
Why size changes how fast a dog ages
Every size completes the same first year: growth, puberty, adult teeth, which is why the columns all read 15 at one (giants 12) and 24 at two. After maturity the curves separate. A small dog adds about 4 human years per dog year, a medium 4 to 5, a large 5 to 6 and a giant 7, so by 10 the gap between a small and a giant dog of the same age is 23 human years and by 16 it is 41. Large mammals usually live longer than small ones; dogs are the exception, and the reason is still being studied.
When each size becomes a senior
The AVMA calls cats and small dogs senior at about 7 and larger breeds at 5 or 6. Read against the chart, those ages land at similar human ages, which is the point: senior is a stage of life, and big dogs reach it sooner.
| Size | Senior from (years) | Human years on the chart |
|---|---|---|
| Small (20 lb or less) | about 7 | 44 |
| Medium (21-50 lb) | about 7 | 47 |
| Large (51-100 lb) | 5 to 6 | 45 |
| Giant (100+ lb) | 5 to 6 | 45 |
What changes at the food bowl
Not the equation, the dog: most seniors move less and fit the inactive adult line, some lose muscle and need the same food or more. How much to feed a senior dog has the calories and grams by weight, and the dog food calculator gives them for your own food.
Puppies and dogs that are not full-grown
Under one year, current weight says nothing about the size class: a 4-month Labrador weighs what an adult Beagle does. Use the expected adult weight, from the breed if you know it, to pick the column, and treat months as a fraction of the first row. The year-by-year guide covers the two methods that do take months.
Mixed breeds and unknown weights
Weigh the dog and read the column for its healthy adult weight. The chart is a population average by size; it will not predict a particular dog, and within a size class breed, weight control and dental care move the real answer by years.
Frequently asked questions
- Is one dog year really seven human years?
- No. Every size reaches about 15 in the first year (12 for giants) and 24 in the second, then the sizes separate. At 7 the chart gives 44-56 against 49 for the old rule, which is close to right only for large dogs around that age and wrong everywhere else.
- How old is a 10-year-old dog in human years by size?
- 56 for a small dog, 60 for a medium, 66 for a large and 79 for a giant breed, a spread of 23 human years between a Chihuahua and a Great Dane of the same age.
- At what age is a dog considered a senior?
- About 7 for small dogs (44 in human years) and 5 or 6 for large and giant breeds (45 and 45), the AVMA thresholds the AKC quotes; medium dogs are usually taken with the small ones. It is a checkpoint for vet visits, not a change in the dog.
- Why do small dogs live longer than large dogs?
- Nobody knows for certain. The AKC reports work by Cornelia Kraus (University of Gottingen) finding that every 4.4 lb (2 kg) of body mass cuts a dog's life expectancy by about a month, with faster growth, earlier age-related disease and more cancer as the likely reasons. In the chart it shows as a giant column that climbs 7 human years a year after year two, against 4 for small dogs.
- How old is a 13-year-old large dog in human years?
- 82. The same dog would be 68 as a small breed, 74 as a medium and 100 as a giant; by 13 the columns are 32 years apart.
- How do I use this chart for a mixed-breed dog?
- By adult weight, not by guessed ancestry: weigh the dog and read the column, 20 lb or less (9 kg) small, 21-50 lb (23 kg) medium, 51-100 lb (45 kg) large, above that giant. If the dog sits on a boundary, use the heavier class.
- What are the weight cut-offs for small, medium, large and giant?
- Small: 20 lb or less (9.1 kg). Medium: 21-50 lb (up to 22.7 kg). Large: 51-100 lb (up to 45.4 kg). Giant: over 100 lb. Use the dog's healthy adult weight, not an overweight one.
- How old is a puppy under one year in human years?
- The chart starts at one year, when every size is about 15. Under that, the first year covers all of growth and puberty, so a 6-month puppy is roughly 8 in human terms by simple scaling; the numbers are a rough guide only, and current weight does not tell you the size class of a puppy, the expected adult weight does.
More guides
- How old is my dog in human years? Table from 1 to 16
Year-by-year table of dog age in human years by the AKC rule and the epigenetic clock, when a dog is senior by size, and the International Cat Care cat table.
- How old is my cat in human years? Table from 1 to 20
Year-by-year cat age in human years (15 at one, 24 at two, then four a year), the life stages, when a cat is senior, and how the dog rules differ.
- How many cups of dog food per day?
Cups of kibble a day by dog weight from the calories on your bag: tables for 300 to 450 kcal per cup, inactive and active adults, and meals.
- How much should I feed my dog? Grams and cups by weight
Daily calories and grams of dry food for dogs from 2 to 50 kg, inactive and active, on foods from 3,400 to 4,000 kcal/kg, with the WSAVA chart range.
Sources
- NRC 2006, Nutrient Requirements of Dogs and Cats — adult, puppy and kitten energy equations
- WSAVA, Calorie Needs for Healthy Adult Dogs (July 2020) — chart range for dogs
- WSAVA, Calorie Needs for Healthy Adult Cats (July 2020) — chart range for cats
- AAHA 2021 Nutrition and Weight Management Guidelines — weight loss at the resting requirement of the target weight
- American Kennel Club, How to Calculate Dog Years to Human Years — the chart by size and the AVMA senior thresholds, read 2026-09-17
Published 2026-09-17, last updated 2026-09-17. Figures are starting points from the published equations: individual animals vary by up to 30%, so adjust by body condition and ask your vet for puppies under 8 weeks, pregnancy, lactation or any illness.