21 cat years in human years
≈ 100 human years. Life stage: Geriatric.
The estimate: about 15 human years for the first year, nine more for the second (so 24 at age two), then roughly four per year after that. At 21 years, that lands at 100.
Part-way through year 21
| 21 yr 0 mo | 100 human years |
|---|---|
| 21 yr 3 mo | 101 human years |
| 21 yr 6 mo | 102 human years |
| 21 yr 9 mo | 103 human years |