If you have taken a dog from a shelter, you may at some point wonder how old your dog is. Determining a dog’s age can be a challenge especially if you have a full-grown adult dog. However, before knowing how old your dog is, it is important to know something about how dogs age.

Dog’s age in human years

You may have heard people say that 1 human year is the equivalent to 7 doggy years. Although that may be true as a general average, it not entirely accurate.

Dogs age and mature must faster than humans do, so, in general, all breeds of dog are the equivalent of 15 human years by the time they are 1-yr old.

Most breeds – large and small – age the equivalent of 4 years for every human year until they are 5 years old. This means that a dog that has lived for 5 years will be the equivalent of 36 years in human terms. At this point, you could say that 1 human year is the same as 7 dog years.

From this point onward, larger breeds tend to age faster than smaller breeds. So, to determine the age of your dog, you also need to consider the type of breed and size of your pet pooch.

How to tell how old your dog is

Unfortunately, dogs, just like humans, develop a number of health conditions in later life. You can use these signs as a way to approximately work out the age of your dog.

Of course, if you have adopted a dog that has been well cared for, then some of these health issues may only show up much later in their life.


Looking at your pet dog’s teeth can be one way to figure how old your dog is. From 1-3 years old, your dog’s teeth will show some dullness and there may be some tartar buildup on the rear teeth. Dogs that are between 3 and 5 yrs. old will have more extensive canine tartar and show more signs of wear. Dogs over 5 years old will have significantly more signs of wear and tear on their teeth.

Color of fur

Dogs older than 7 years old may start to show signs of gray around the muzzle.


Older dogs tend to have more hearing problems and may show signs of aggressiveness because they get startled easily.


You may notice that dogs in their later years have a cloudy appearance in their eyes.