Dog & Cat Age Calculator
Your pet's age in human years, by breed size
Dog and Cat Age Chart in Human Years
| Age | 🐶 Small | 🐶 Medium | 🐶 Large | 🐶 Giant | 🐱 Cat |
|---|---|---|---|---|---|
| 1 | 15 | 15 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 | 24 | 24 |
| 3 | 28 | 29 | 30 | 31 | 28 |
| 4 | 32 | 34 | 36 | 38 | 32 |
| 5 | 36 | 39 | 42 | 45 | 36 |
| 6 | 40 | 44 | 48 | 52 | 40 |
| 7 | 44 | 49 | 54 | 59 | 44 |
| 8 | 48 | 54 | 60 | 66 | 48 |
| 9 | 52 | 59 | 66 | 73 | 52 |
| 10 | 56 | 64 | 72 | 80 | 56 |
| 11 | 60 | 69 | 78 | 87 | 60 |
| 12 | 64 | 74 | 84 | 94 | 64 |
| 13 | 68 | 79 | 90 | 101 | 68 |
| 14 | 72 | 84 | 96 | 108 | 72 |
| 15 | 76 | 89 | 102 | 115 | 76 |
| 16 | 80 | 94 | 108 | 122 | 80 |
Small <10 kg, medium 10–25 kg, large 25–45 kg, giant >45 kg (adult weight). Values are rounded estimates based on AVMA and AAHA guidance.
How Old Is My Dog or Cat in Human Years?
A size-aware dog age calculator and a cat age calculator in one
The old “multiply by 7” rule is wrong: dogs and cats grow up very fast in their first two years and then age more slowly. This calculator uses the method recommended by veterinary associations: the first year equals about 15 human years, the second adds about 9 (so a 2-year-old pet is roughly 24), and every year after that adds 4 human years for cats and small dogs, 5 for medium dogs, 6 for large dogs and 7 for giant breeds, because bigger dogs age faster. Enter the age in years and months, choose dog or cat and the dog's size, and you get the human age, the current life stage and the result of the 2020 UCSD epigenetic formula (16 × ln(age) + 31). The chart below lists every age from 1 to 16.
Features
Dog size matters
Small, medium, large and giant breeds
Cat age
Indoor and outdoor cats
Full age chart
1–16 years for every size
DNA formula
UCSD epigenetic clock for dogs
Dog and Cat Years Explained
Quick conversions
- 1 year = 15 human years (dogs and cats)
- 2 years = 24 human years
- 5 years: small dog 36 · large dog 42 · cat 36
- 10 years: small dog 56 · medium 64 · large 72 · giant 80 · cat 56
- 15 years: small dog 76 · cat 76
Senior age by size
- Small dogs (<10 kg): senior from about 10 years
- Medium dogs (10–25 kg): from about 8 years
- Large dogs (25–45 kg): from about 7 years
- Giant dogs (>45 kg): from about 6 years
- Cats: senior from 11, super senior from 15
Frequently Asked Questions
Is one dog year really seven human years?
No. That rule ignores the fast growth of the first two years and the effect of size. A one-year-old dog is already sexually mature, closer to a 15-year-old human, and a 2-year-old is roughly 24.
Why do large dogs age faster?
Large and giant breeds have shorter life expectancies and reach old age sooner, so each year after the second counts for more human years: about 6–7 instead of 4–5 for small dogs.
How do I calculate my cat's age in human years?
Count 15 for the first year, 24 at two years, then add 4 for each further year. A 10-year-old cat is about 56 and a 15-year-old about 76 in human years.
What is the UCSD dog age formula?
A 2020 study from the University of California San Diego compared DNA methylation in Labradors and humans and proposed human age = 16 × ln(dog age) + 31. It fits medium-sized dogs best and gives a 1-year-old dog about 31 human years.
Which size should I choose for a mixed breed?
Use the expected adult weight: under 10 kg small, 10–25 kg medium, 25–45 kg large and over 45 kg giant.
How long do dogs and cats live?
Small dogs often live 13–16 years, large dogs 10–12 and giant breeds 8–10. Indoor cats commonly reach 13–17 years, and many live past 20.