Easy-to-Follow Dog Years to Human Years Conversion

Updated April 7, 2022
Senior man with look alike dog.

If you've ever wondered how old your dog would be if they were a person, you're not alone. Discovering your dog's human age is both fun and can also be an important way to understand their needs based on which life stage they fall into. Uncover the most accurate method for converting dog years to human years -- no tricky math equations required.

Converting Dog Years to Human Years

It was long believed that each year of a dog's life was equivalent to seven human years. Some experts suggest that this calculation was based on the assumption that the average person lives to be about 70 years old, whereas the average dog lives for 10 years. Although it's easy to multiply your dog's real age by 7, new data suggests there is a more accurate way to figure out your dog's relative age in "human years."

To get a rough idea of an average dog's equivalent human age, depending on their size, reference this chart:

Dog's Real Age

Small Dog (less than 25 lbs.)

Medium Dog (26-50 lbs.) Large Dog (51-100 lbs.) Extra Large Dog (101 lbs. and up)
Puppy (birth to 9 months) birth to 12 years birth to 12 years birth to 10 years birth to 8 years
1 year old 15 years 15 years 12 years 10 years
2 years old 24 years 24 years 24 years 20 years
3 years old 28 years 28 years 28 years 30 years
4 years old 32 years 32 years 32 years 37 years
5 years old 36 years 36 years 36 years 44 years
6 years old 40 years 41 years 42 years 51 years
7 years old 44 years 46 years 48 years 58 years
8 years old 48 years 51 years 54 years 65 years
9 years old 52 years 56 years 60 years 72 years
10 years old 56 years 61 years 66 years 79 years
11 years old 60 years 66 years 72 years 86 years
12 years old 64 years 71 years 78 years 93 years
13 years old 68 years 76 years 84 years 100 years
14 years old 72 years 81 years 92 years 107 years
15 years old 76 years 86 years 98 years 114 years
16 years old 80 years 91 years 102 years 121 years
17 years old 84 years 96 years 108 years 128 years
18 years old 88 years 101 years 114 years 135 years

Keep in mind, this is a very rough estimate based on information and conclusions from the the American Veterinary Medical Association (AVMA), as well as from this study in the journal Cell Systems, which only examined Labrador Retrievers. The correlation begins to break down at some point, but you at least have a much more reasonable estimate of your dog's age in equivalent human years, just by referencing the weight ranges in this chart.

In the article published in Cell Systems, the researchers looked at Labrador DNA patterns to figure out similarities between canine and human developmental milestones. A dog's breed and size play a big roll in figuring out their life stage and equivalent human age. Typically, smaller dogs who roughly average 25 pounds or less tend to live longer lives and spend more time in what humans think of as their "senior years." On the other hand, larger dogs who weigh anywhere from 51 to 100 pounds on average often live shorter lifespans, anywhere from 8 to 12 years, give or take a few years.

Find a More Accurate Equivalent Human Age

You dog's breed, genetic characteristics, overall health, weight, and a variety of other factors influences their estimated equivalent age. Both the AVMA and the American Kennel Club (AKC) suggest that a medium-sized 1-year-old dog is equivalent to a 15-year-old human, and a 2-year-old dog is roughly equivalent to a 24-year-old human. At 3 years of age, dogs are roughly 28 years old (or 30 years old, for very large breeds) in their equivalent human age.

At 4 years of age, dogs are roughly 32 years old (except for very large breeds, who are closer to 37 years old at this point in their development), and at 5 years old, dogs are around 36 years of age in equivalent human years (and very large dogs are already in their 40s by this time).

After a dog reaches a real age of 5 years, you have to do a bit more math to get a more accurate estimate. To figure out your dog's equivalent human age, for a small breed, add 4 to their equivalent human age. So, a small dog's equivalent human age would be 40 when their real age is 6. For medium dogs, add 5 to their equivalent human age past their real age of 5 years. For large dogs, add 6 to their equivalent human age, and for very large dogs, add 7 to their equivalent human age after their real age passes 5 years.

Although this new calculation seems to be more accurate than the previous 7-to-1 year ratio, it's still only an estimate. It likely won't be correct for every dog, and it in no way predicts how long your dog is likely to live. This method just gives you a rough guess of how old your dog is, compared to a human's age.

Canine Life Stages

Taking a close look at the physical and mental developmental milestones dogs go through during each phase of their life has helped experts develop this new age comparison. According to the American Animal Hospital Association, there are four life stages that dogs go through. Each stage has different care requirements that dog owners should be aware of.

  • Puppy: Puppyhood starts as soon as a dog is born and lasts until they're between 6 months and 9 months of age. During this time, puppies grow rapidly in size. Exactly when this initial puppy stage ends depends on the breed and size of the dog. Some smaller dog breeds may be their full size by the end of the stage.
  • Young adult: Adolescence begins around 6 to 9 months and lasts through approximately until dogs are 3 to 4 years old. A dog's physical growth tends to slow during young adulthood (they should reach their full grown size early on in this stage), and instead they develop mentally. This is often referred to as the "awkward teenage phase," as dogs learn to socialize, often push their limits, and reach sexual maturity.
  • Mature adult: A dog is a true adult from the age of 3 to 4 years until they reach the last 25 percent of their estimated lifespan. Longevity varies based on the breed and size of a dog. For example, the Miniature Pinscher has a lifespan of around 15 years, so their mature adulthood would last until they're just over 11 years old, whereas an Alaskan Malamute with a life expectancy of 10 years would move into the next stage at 7.5 years old. During mature adulthood, dogs may still grow, but their development plateaus and their health may begin to decline with age.
  • Senior: After your dog reaches the final 25 percent of their expected lifespan, they are a senior until their final day. Senior dogs are no longer developing or growing, but you will likely see changes with age. They may experience decreased mobility, develop diseases, and show other signs of decline.

Given the fact that dogs develop more quickly during the earlier stages, then their growth appears to level out, it's understandable that each year of their life cannot be measured equivalently to human years.

Consider Size and Breed

The general size of a dog affects how rapidly they develop, as does breed. A small breed dog under 25 pounds could easily live to be 18 years old, whereas a large or giant breed dog weighing more than 120 pounds may not make it past 8 or 10 years old. Understandably, a Chihuahua and an English Mastiff who are both 6 years of age would be in vastly different life stages, and their relative age is not equivalent in human years.

A black labrador retriever puppy plays with an adult Vizsla.

Use Caution When Converting Dog Years

While it can be fun to know exactly how old your dog is in comparison to human age, it's more important to focus on life stage. By understanding which phase your dog falls into, you can ensure that you're giving them the training and care they need to develop appropriately. A life stage calculator that takes breed into consideration can give you a more accurate estimate of age.

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Easy-to-Follow Dog Years to Human Years Conversion