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About the dog age calculator
"One dog year is seven human years" is a myth — dogs grow up much faster at the start and then age at a speed that depends on their size. A one-year-old dog is already like a 15-year-old teenager, and at two it is like a young adult of 24. After that, small dogs age slowly and giant dogs fast.
Enter your dog's age in years and months and choose its size. You get its age in human years and its life stage: puppy, young adult, adult or senior.
How to use it
- Type your dog's age in years and months
- Choose the size: small, medium, large or giant
- Read the age in human years and the life stage
Dog age chart
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 | 24 |
| 3 years | 28 | 29 | 30 | 31 |
| 5 years | 36 | 39 | 42 | 45 |
| 7 years | 44 | 49 | 54 | 59 |
| 10 years | 56 | 64 | 72 | 80 |
| 12 years | 64 | 74 | 84 | 94 |
| 15 years | 76 | 89 | 102 | 115 |
Sizes: small up to 9 kg (20 lb), medium 10–23 kg, large 23–40 kg, giant over 40 kg (90 lb).
How it is worked out
- First year: 15 human years
- Second year: 9 more (24 in total)
- After that: 4 human years per year for small dogs, 5 for medium, 6 for large, 7 for giant breeds
The calculator also shows a newer estimate from DNA research: 16 × ln(dog age) + 31. It fits the early years well, but it does not take size into account.
When is a dog a senior?
Small dogs often become seniors around 10–11 years, medium dogs around 8, large dogs around 6–7 and giant breeds as early as 5. Senior dogs benefit from regular vet check-ups, softer exercise and food made for older dogs.
Frequently asked questions
Is one dog year really seven human years?
No. Dogs mature very fast in their first two years — a one-year-old dog is more like a 15-year-old. After that, the rate depends on size.
How old is a 5-year-old dog in human years?
About 36 for a small dog, 39 for a medium dog, 42 for a large dog and 45 for a giant breed.
Why do big dogs age faster?
Large breeds grow quickly and have shorter lives on average. Scientists are still studying exactly why, but the pattern is clear in every breed survey.
What size is my dog?
Use its adult weight: small up to 9 kg (20 lb), medium 10–23 kg (21–50 lb), large 23–40 kg (51–90 lb), giant over 40 kg.
Is this a medical tool?
No. It is a fun guide based on common charts. For your dog's health, ask your vet.
Good to know
- Your dog's details are saved in this browser
- For cats, use the Cat Age Calculator
- Nothing you type is sent anywhere
Related tools
- Cat Age Calculator — cat years to human years
- Age Calculator — your own exact age
- Date Calculator — days between dates
- Countdown to Date — count down to a birthday
- Kg to Lbs — your dog's weight in pounds
