How To Figure Out A Dog's Age Based on Features

If you're trying to figure out a dog's age, the first thing you need to know is its biological age.
How To Figure Out A Dog's Age Based on Features
Francisco María García

Written and verified by the lawyer Francisco María García.

Last update: 22 December, 2022

Once you know a dog’s biological age, it’s easy to convert into dog age years. This information is vitally important, because it allows the owner to make decisions about important health matters, like for example diet, neutering or spaying, taking the dog’s real age into account. The answer to many key health questions such as these will depend to a large extent on the dog’s age.

But problems can occur when, for some reason or other, you don’t have accurate information about the dog’s biological age. However, don’t despair! There are some ways to get a good approximation of the dog’s age, taking into account the following:

  • Teeth
  • Size
  • Musculature
  • Condition of fur
  • Eyes


It is well known (or perhaps just to horse experts) that examining a horse’s teeth is a great way to find out not just about its age, but also about the state of its health in general. But what about with dogs?

Checking out a dog’s teeth can be a great way to help you get an idea of its age. Dogs have all their milk teeth until they are 8 weeks old. By the time they are seven months old, though, they will have their full set of permanent, adult teeth.

So if a dog already has all of its permanent teeth, but they still look white and are free of blemishes, the best guess would be that the dog is between 18 months and 2 years old.

Once the dog is two years and older, its teeth start to turn yellow, and a build up of tartar will likely be visible.

When the dog is between 3 and 5 years old, you’ll be able to notice signs of wear and tear on its incisors. 

Then, once it’s reached the grand old age of 5, a build-up of tartar will likely cause gingivitis – you’ll notice this due to the red color of the dog’s gums, which may also be inflamed.

These are some of the ways in which a dog’s teeth can give you clues as to its age. However, there are some factors which affect the condition of the teeth – and hence the age estimate you can make on that basis – such as the dog’s species or predisposition to biting.


If a dog is still in the process of growing, it is likely still under the age of two. However, small dogs are an exception to this, as they usually reach their full adult size at the end of their first year. And on the other end of the scale, members of very large species frequently continue to growth beyond the age of two.


A more defined musculature is an indication of youth, since the younger the dog, the higher its activity levels are likely to be. The opposite occurs with older dogs – their bones may be more noticeable, and they may carry more fat on their bodies. Bear in mind, though, that body fat also depends on other factors like the diet and exercise of the individual dog.


A young dog’s coat will be finer and softer, while older dogs often have a coarser, shaggier and thicker pelt. It’s also common for adult dogs to have gray hairs around their snouts.

Crunching The Numbers

As we said at the outset, the starting point is to have an idea of the dog’s biological age. we must start by having the biological age of a dog. And bear in mind that it’s not possible to calculate the “dog” age of animals that are less than two years old, because the first step of the number crunching process is to subtract two. It goes as follows: take the dog’s biological age, subtract two, and then multiply the resulting number by 4. Then, add 21 and you’ll get the age in “dog years” of the animal in question.

For example, if you have a dog whose biological age is 10 years old, its age in dog years will be 53. The calculation is done as follows:

10 – 2 = 8

8 x 4 = 32

32 +21 = 53

Of course, don’t forget that we’re talking in terms of estimates and best guesses. This is a method that doesn’t take into account the size or breed of the dog, so could never be totally accurate. 

In fact, this calculation works much more reliably for smaller dogs than larger ones. For example, a 10-year-old Great Dane would actually be around 80 in dog years – but according to this calculation, it would only be 53. Although it doesn’t work so well for the biggest species, it can give you a very good estimation for small and medium-size dogs.

And remember that, even though we have these handy tricks at our disposal, only a specialist who has done a complete physical examination of the dog will be able to make a calculation that’s 100% accurate. 

Main image source: Jeff Ro

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.