Dog Years to Human Years Calculator

This article was updated on May 2nd, 2023

You can use two different methods to calculate your dog’s age in human years: 1) determine the based on your dog’s breed (recommended for purebred dogs), 2) use your dog’s size and weight (recommended for mixed breed dogs).

Don’t Use the 7x Rule to Calculate Your Dog’s Age in Human Years

Many people think that a dog year is equivalent to 7 human years. However, this 7x ratio is NOT true for most breeds. For example, a 10-year-old male neutered Chihuahua would be 70 years old using the 7x rule. In reality, our calculator below shows that 45 years old is a better estimate (Chihuahuas have an average life expectancy of 15.5 years).

Convert Dog Years to Human Years Based on Your Dog’s Breed [Calculator]

When estimating how old your dog is in human years, the primary factor to consider is your dog’s breed. Research also shows that neutering status, and, to a lesser extent, sex are important factors to take into account. We have taken these key factors into account in our calculator below:

Small breeds live as much as 50-80% longer than larger breeds and experience the negative effects of aging later in life compared to large breeds. If your dog is a mixed breed, a reliable way to convert your dog’s age to human years is to use your dog’s size or weight.

If Your Dog is a Mixed Breed, Use “Size” to Estimate Human Years:

All in all trying to figure out how old your dog is in ‘dog years’ v ‘human years’ isn’t an exact science. If your dog is mixed breed or if you don’t know your dog’s breed, the next most important factor to consider is size/weight.

To make it a little easier, we have put together this table that translates ‘dog years’ to ‘human years’ for small, medium and large breeds.

See this infographic to find out your dog’s age in human years based on size:

But if you don’t know when your dog was born, how can you best estimate your dog’s age? Read our post on “How Old Is My Dog?” for easy tips to estimate how old your dog really is.

Studies Used to Build Our “Dog Years to Human Years” Calculator

Estimating a dog’s age in human years is not simple. We have reviewed data from multiple studies to conclude that a breed-based calculator is best. To build the formula behind our calculator, we have used the following studies:

• Mortality in over 350,000 insured Swedish dogs from 1995-2000.
• Lifespan of companion dogs seen in three US veterinary clinics.
• Mortality data on 5663 deceased dogs registered with the UK Kennel Club. 
• “Do Female Dogs Age Differently Than Male Dogs?” from The Journal of Gerontology.
• Longevity and Mortality of Dogs in England in The Journal Of Veterinary Medicine.

Related posts: Pictures of Teeth by Dog’s Age: Veterinarians use many clues to estimate a dog’s age. One thing that we examine is the dog’s teeth. In this article, we will review what teeth can tell you about a dog’s age – with pictures of teeth by dog age.