The very familiar formula for calculating dog age in human years is their actual age times 7. While this provides a fair measure of the equivalent chronological age in the earlier years, the calculation is inaccurate for combined variables of age plus dog size. Larger dogs age faster and an accurate formula is not linear, so the years times 7 is very general.
Try the following table instead for pets aged 1 through 20 years old as adapted from a poster in my veterinarian’s office that listed estimates for up to 25 years old. 20 seemed sufficient, so for ages or weights not shown, you may want to contact the Guiness Book of World Records!
Table for Cat or Dog Age in Human Years
| Age | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
| Weight | Instructions: Find actual age ABOVE, then down by weight for dog age in human years. | |||||||||||||||||||
| 0-20 | 7 | 13 | 20 | 26 | 33 | 40 | 44 | 48 | 52 | 56 | 60 | 64 | 68 | 72 | 76 | 80 | 84 | 88 | 92 | 96 |
| 21-50 | 7 | 14 | 21 | 27 | 34 | 42 | 47 | 51 | 56 | 60 | 65 | 69 | 74 | 78 | 83 | 87 | 92 | 96 | 101 | 105 |
| 51-90 | 8 | 16 | 24 | 31 | 38 | 45 | 50 | 55 | 61 | 66 | 72 | 77 | 82 | 88 | 93 | 99 | 104 | 109 | 115 | 120 |
| 91 Up | 9 | 18 | 26 | 34 | 41 | 49 | 56 | 64 | 71 | 78 | 86 | 93 | 101 | 108 | 115 | 123 | 131 | 139 | ||
*Note: Values extracted from a poster at our vet’s office with data by Fred L. Metzger, DVM DABVP
Yes, the estimate works for cats or kittens, too! You can use the same table, yet for your cat you should only need the small dog 0-20 lbs data. Having a small breed puppy or mutt and a pet kitten born around the same time while maintaining reasonable health would mean having pets that should age at the same rate in human years.
