Popular calculator
Dog & Cat Age Calculator
Convert dog or cat years to human years by size, with a full age chart.
Quick answer
How do you convert dog years to human years?
A dog's first year equals about 15 human years and the second year adds 9 (24 total). After that, add about 4 years per year for small dogs, 5 for medium, 6 for large and 7 for giant breeds. A 10-year-old medium dog is about 64 in human years.
- Count the first year as 15 human years.
- Add 9 for the second year (24 at age 2).
- Multiply the remaining years by 4, 5, 6 or 7 depending on size.
- Example: medium dog age 10 → 24 + 5 × 8 = 64 human years.
Year 1 = 15 human years • Year 2 = 24 • then +4 (cats, small dogs), +5 (medium), +6 (large) or +7 (giant) per year • DNA formula: 16 × ln(dog age) + 31
⚡ Answer updates as you type · Enter = calculate · Esc = reset
- First year = 15 human years.
- Second year adds 9 more (= 24 at age 2).
- Each year after that adds about 5 human years for a medium dog.
- 24 + 5 × (5 − 2) = 39 ≈ 39 human years.
| Dog years | Human years |
|---|---|
| 1 | 15 |
| 2 | 24 |
| 3 | 29 |
| 4 | 34 |
| 5 | 39 |
| 6 | 44 |
| 7 | 49 |
| 8 | 54 |
| 9 | 59 |
| 10 | 64 |
| 11 | 69 |
| 12 | 74 |
| 13 | 79 |
| 14 | 84 |
| 15 | 89 |
| 16 | 94 |
Estimates for fun and general guidance. Breed, health and genetics vary — ask your vet about your pet's care.
Convert your dog's or cat's age to human years, using vet-style charts by size, plus the newer DNA-based dog formula.
About this Dog & Cat Age Calculator
The Dog & Cat Age Calculator converts your pet's age into human years. Dogs age at different speeds depending on size, so it uses a vet-style chart for small, medium, large and giant dogs, a separate chart for cats, and also shows the newer DNA-based dog formula.
What you'll need
- • Dog or cat
- • Dog size by adult weight
- • Age in years and months
How it works
- 1. Pick dog or cat.
- 2. Choose your dog's size.
- 3. Enter the age.
- 4. Read human years, life stage and the full chart.
- 5. Copy, share or download the PDF.
Worked example
A 7-year-old cat is 24 + 4 × 5 = 44 human years. A 7-year-old large dog is 24 + 6 × 5 = 54.
Related searches
Dog & Cat Age Calculator FAQ
What is the Dog & Cat Age Calculator?
The Dog & Cat Age Calculator is a free online tool that helps you convert dog or cat years to human years by size, with a full age chart.
How do I use the Dog & Cat Age Calculator?
Open the Dog & Cat Age Calculator, enter the requested values, and review the instant estimate on the page.
Is the Dog & Cat Age Calculator free?
Yes. The Dog & Cat Age Calculator is free to use on Fast Online Calculator and does not require an account.
Is one dog year really 7 human years?
No — that's a myth. Dogs grow up very fast in the first two years (about 24 human years), then age 4 to 7 years per year depending on size.
How old is a 1-year-old dog in human years?
About 15 human years — roughly a teenager.
How old is a 10-year-old cat in human years?
About 56 human years: 24 for the first two years plus 4 for each of the next 8.
Why do big dogs age faster?
Large and giant breeds have shorter lifespans and reach senior age sooner, so each year after age 2 counts as more human years.
What is the DNA dog age formula?
A 2019 UC San Diego study found human age ≈ 16 × ln(dog age) + 31, based on DNA changes. It suggests young dogs age even faster than older charts show.
Related calculators
Time
Age Calculator
Calculate age in years, months, and days from a date of birth.
Time
Days Between Dates
Count calendar days, weeks, months and business days between two dates.
Time
Date Calculator
Add or subtract days, weeks, months, and years from a start date.
Health
BMI Calculator
Estimate body mass index from height and weight for a quick health category check.