Meddor
The dog chart
In dogs, the first two years count for a lot, then each year counts for more the bigger the dog: large dogs age faster. Size means their adult weight.
| Age | Up to 9 kg (20 lb) | 9 to 23 kg | 23 to 41 kg | Over 41 kg (90 lb) |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 | 24 |
| 3 years | 28 | 28 | 30 | 32 |
| 5 years | 36 | 37 | 40 | 42 |
| 7 years | 44 | 47 | 50 | 56 |
| 10 years | 56 | 60 | 66 | 78 |
| 12 years | 64 | 69 | 77 | 93 |
| 15 years | 76 | 83 | 93 | 115 |
These figures come from the chart published by AAHA, taken from a reference veterinary handbook for owners. For dogs over 41 kg, it stops at 16 years.
The cat chart
A cat is about 15 in human years at 1 year old, 24 at 2, then adds about 4 human years each year.
| Age | In human years |
|---|---|
| 6 months | 10 |
| 1 year | 15 |
| 2 years | 24 |
| 5 years | 36 |
| 10 years | 56 |
| 15 years | 76 |
| 20 years | 96 |
Under 1 year, the calculator follows International Cat Care’s chart: about 2 human years at 2 months, 10 at 6 months.
What science says
These charts are guides, not measurements. In 2020, a team at the University of California San Diego compared how the DNA of 104 Labradors ages with that of humans. It confirms that a dog ages very fast at first, then more slowly. But it studied only one breed, and its authors say so: other breeds could age differently.
What their age means for vet visits
Vets divide an animal’s life into stages, because their care needs change.
- Cats: kitten up to 1 year, young adult from 1 to 6, mature adult from 7 to 10, senior over 10. AAHA and AAFP recommend at least one visit a year, and at least every 6 months for a senior cat.
- Dogs: puppy until rapid growth stops (around 6 to 9 months depending on size), young adult until 3 or 4 years, then mature adult, and senior for the last quarter of their expected lifespan, which depends on breed and size. AAHA recommends an exam every 6 to 12 months for adults, and at least every 6 months for seniors.
Frequently asked questions
Why not seven years per year?
Because an animal ages very fast in its first year, then more slowly. The chart gives 15 human years at 1 year, 24 at 2, then a few human years per year, more the bigger the dog.
My dog is a mixed breed: which size should I pick?
Their adult weight, or the weight expected if they’re still growing. Your vet can help you estimate it.
My cat is 15: is that old?
It’s a senior cat, the equivalent of about 76 human years. They should see their vet at least every 6 months.
Sources
- Zoetis, published by AAHA, “My pet’s physiological age”, 2019: cat chart, from the AAFP-AAHA Feline Life Stage Guidelines (2010), and dog chart by size, from the Dog Owner’s Home Veterinary Handbook (2007).
- International Cat Care, “How old is your cat?”: kitten ages.
- Creevy et al., “2019 AAHA Canine Life Stage Guidelines”, JAAHA, 2019: dog life stages and exam frequency.
- Quimby et al., “2021 AAHA/AAFP Feline Life Stage Guidelines”, JAAHA, 2021: cat life stages and visit frequency.
- Wang et al., “Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome”, Cell Systems, 2020.