Pet Age Calculator
Human age = 15 (1st year) + 9 (2nd year) + 4-6 × each additional year (varies by breed/species)15 + 9 + 5 = 29 human years
Free online tool
Pet Age Calculator
Select your pet type and enter their age to find the approximate equivalent in human years.
Instant calculation
Calculate Pet Age in Human Years
Enter your pet's age and choose their type.
Your result
Calculation
Your numbers stay in this browser. Nothing is uploaded or saved.
Three clear steps
How to use this calculator
- 01
Enter pet age
Type your pet's age in years (decimals are OK, for example, 0.5 for six months).
- 02
Choose pet type
Enter the number matching your pet: 0=Small Dog, 1=Medium Dog, 2=Large Dog, 3=Cat.
- 03
See human equivalent
The result shows the approximate human age for your pet.
The formula
How this calculation works
Dogs and cats age rapidly in their first two years, then more slowly. Estimates based on AAHA canine and feline life stage guidelines. Individual health, breed and genetics also influence actual aging. This is not a veterinary health assessment.
Check the method
Worked examples
Each example follows the same formula used by the calculator.
3-year-old medium dog in human years?
15 + 9 + 5 = 29 human years≈ 29 human years5-year-old cat in human years?
15 + 9 + (3 × 4) = 36 human years≈ 36 human yearsCommon questions
Questions about this calculation
Is the 7 dog years to 1 human year rule accurate?
No. The 7:1 ratio is an oversimplification. Dogs age much faster in their first two years (about 15 human years in year 1, 9 in year 2) and then 4-6 years per additional year depending on size.
Why do small and large dogs age differently?
Smaller dogs tend to live longer and age more slowly after age 2. Large dogs age faster, each year after age 2 adds about 6 human years versus 4 for small dogs.
How are cat years calculated?
Cats age similarly to small dogs: about 15 human years in the first year, 9 in the second, and 4 human years per year after that.
How accurate is the pet age calculation?
The estimates follow AAHA canine and feline life stage guidelines. They are approximations — individual health, breed and genetics also influence actual aging. This is not a veterinary health assessment.
Can I enter a decimal age like 0.5 for a 6-month-old pet?
Yes. Enter 0.5 for 6 months, 0.25 for 3 months, etc. The calculator handles fractional years.
Continue calculating