Cat Age Calculator
See your cat’s age as an approximate human-age comparison.
How cat years compare
The usual comparison is 15 human years at age one, 24 at age two, then roughly four human years for each cat year. Early milestones and intermediate months are approximate. This is not a measure of health or expected lifespan.
Age comparisons: Cats Protection’s age comparison. Life-stage labels follow AAHA/AAFP guidance: kitten under one, young adult one through six, mature adult seven through ten, and senior over ten.
How to enter your cat’s age
Enter completed years and any additional months. For a cat aged two years and six months, enter 2 and 6. For a six-month-old kitten, enter 0 and 6. Do not enter 2.5 in the years field: the tool uses separate whole-number inputs.
The supported range is one month to 30 years. If your cat’s birthday is unknown, use the age estimate provided by the shelter or your vet and treat the result as approximate too.
How cat years compare with human years
The comparison is not a constant seven-year multiplier. Cats Protection’s age guide compares the first cat year with about 15 human years and the second with about 24. Each year after that adds roughly four. Our tool estimates the intervening months and rounds to a whole human year.
| Cat age | Approximate human age |
|---|---|
| 6 months | 10 years |
| 1 year | 15 years |
| 2 years | 24 years |
| 5 years | 36 years |
| 10 years | 56 years |
| 15 years | 76 years |
A worked example
A five-year-old cat is three years beyond the two-year milestone. The calculation is 24 + (3 × 4), giving about 36 human years. That comparison helps put an age in familiar terms; it is not a measure of how healthy that particular cat is.
Understanding the life-stage label
The labels follow the AAHA/AAFP feline life stages: kitten under one year, young adult from one through six, mature adult from seven through ten, and senior over ten. The calculator changes to “Senior” once the entered age exceeds ten years.
Use the actual age, rather than the human comparison, when speaking with your vet. “Twelve years old” is the relevant detail for your cat’s records. “About 64 human years” is an explanatory analogy.
If the result prompts questions, keep a short list for the next visit: which changes to watch for, whether the current routine still suits your cat, and what follow-up your vet recommends. The number itself cannot answer those questions.
Frequently asked questions
Does this predict how long my cat will live?
No. A human-age comparison is not a lifespan forecast. The tool does not collect medical history or assess health.
Why might another chart give a different answer?
Charts use approximate comparisons, particularly during kittenhood. This tool uses milestone values and estimates between them. Small differences are not evidence that your cat is developing too quickly or too slowly.
Can I calculate an adopted cat’s birthday?
No. You must supply an age. The tool cannot determine a birthday from appearance, weight or behavior.
Are my entries saved?
No entries are submitted by the calculator. The result is calculated in your browser and is not added to a pet record.
By The Cats Hub editorial team. Updated September 28, 2026.