Cat Age Calculator
Convert your cat's age into an approximate human age.
Approximate human age
36years
Approximate only — health, breed and lifestyle affect how cats age.
v1.0 · Reviewed September 2026
How this is worked out
The first year counts as 15 human years, the second adds 9, and every year after that adds 4.
Worked example
- 5 years old
24 for the first two years, plus 3 × 4
36 human years
Assumptions and limits
- An approximation used widely by veterinary organisations, not a precise measure.
- Indoor and outdoor cats age differently in practice, and breed and health matter more than the arithmetic.