Dog Age Calculator

What this does

So you want to know how old your dog really is in human terms. This works it out. Put in your dog's age, pick their size, choose which method you want, and it gives you the human age equivalent. And it does not use that old multiply by seven rule, because that one is wrong. It uses two better-known methods instead, one from vets and one from a genetics study, so you can compare them.

How to use it

1. Enter your dog's age in years.
2. Pick the size category, small, medium, or large, since size changes how a dog ages.
3. Choose a method, the AVMA chart or the University of California formula, then press Calculate.

Try both methods on the same dog and see how close they land.

The two methods

You get two ways to work it out, because there is no single perfect answer, and it is interesting to see them side by side.

The AVMA method is the vets' chart. It follows the guideline used by the American Veterinary Medical Association and the American Kennel Club. The first year of a dog's life counts as about 15 human years, the second year brings the total to around 24, and after that each dog year adds roughly four to six human years, with larger dogs adding more. This is the one that uses your size choice, because a large dog and a small dog of the same age are at different stages of life.

The University of California method is the science one. In 2020, researchers at UC San Diego studied the DNA of Labrador Retrievers and found that dog age maps onto human age along a curve, not a straight line. Their formula is this:

human age = 16 × ln(dog age) + 31

Here ln is the natural logarithm. So you take the natural log of your dog's age, multiply that by 16, and add 31. For a 5 year old dog, that lands at about 57 human years. It gives the same answer whatever size you pick, since it came from one study on one breed, so do not be surprised when changing the size does not move that number.

Why the times seven rule is wrong

You have probably heard that one dog year equals seven human years. It is a tidy rule, and it is wrong. It came from simply dividing the old human life expectancy of about 70 by a dog's roughly 10 years, with no biology behind it.

Here is what actually happens. Dogs grow up fast and then slow down. A one year old dog is not like a seven year old child, it is closer to a teenager, already fully grown and able to have puppies of its own. That is why both methods jump to around 15 human years in the first year. After that the ageing slows, which is exactly what the logarithm in the UC formula captures.

Size matters too, and it matters more as a dog gets older. Small dogs tend to live longer and age more gently, while large and giant breeds age faster, which is why a big dog is often a senior by five or six, and a small dog not until later. That is the whole reason the AVMA method asks for a size.

Dog age chart

Here is a quick chart for some common ages, using the AVMA method, so you can see roughly where your dog sits. The numbers are human year equivalents.

Why your dog's age matters

This is more than a fun number. Knowing roughly where your dog is in life helps you look after them better. As dogs move into their senior years, vets often suggest more regular check ups, some changes to diet and weight, and a closer eye on joints, teeth, hearing, and sight. Catching that shift early is the useful part. That said, a chart is only an estimate, and your vet, who can actually examine your dog, is the best judge of their real life stage and health.

Questions people ask

References

1. Wang, T., et al. Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome. Cell Systems, 2020. https://www.cell.com/fulltext/S2405-4712(20)30203-9
2. University of California, Davis, School of Veterinary Medicine. Calculating Your Dog's Age. https://healthtopics.vetmed.ucdavis.edu/health-topics/canine/calculating-your-dogs-age
3. American Veterinary Medical Association. Senior Pets. https://ebusiness.avma.org/files/productdownloads/SeniorPets_En.pdf