PetGrit

Dog & Cat Age Calculator

The “multiply by 7” rule is wrong — pets age fast early and slow down later. This calculator converts your dog’s age with the 2020 epigenetic-clock formula and your cat’s age with the AAHA/AAFP life-stage scale, then tells you which life stage they’re in.

Pet

Use decimals for months — 0.5 = six months.

In human years, your pet is about

— years old

How to use it

  1. 1 Choose dog or cat.
  2. 2 Enter their age in years (decimals are fine — 0.5 for six months).
  3. 3 See their age in human years and their current life stage.

Why this matters

A one-year-old dog is closer to a 31-year-old human than a 7-year-old — they mature fast, then aging slows. The naive ×7 rule misses this badly, especially in the first two years. Dogs here use human ≈ 16 × ln(age) + 31 from a 2020 epigenetic-aging study; cats use the veterinary life-stage convention (15 human years in year one, 24 by year two, then about four per year).

Frequently asked questions

Is one dog year really seven human years?

No — that rule is a myth. Dogs age much faster in their first two years and more slowly afterward. A more accurate dog formula is human age ≈ 16 × ln(dog age in years) + 31.

How old is my cat in human years?

By the standard veterinary scale, a cat is about 15 human years at age one, 24 at age two, and adds roughly four human years for each year after that.

Does breed or size change the answer?

Yes, somewhat. Large and giant dog breeds age faster than small breeds, so treat the number as a solid estimate rather than an exact age. Cats vary less.

Keep going

Dog & Cat Feeding Calculator Daily calories and cups, from the vet-standard RER/MER formula. Puppy & Kitten Vaccine Schedule A dated core-vaccine timeline from your pet’s birth date. Dog & Cat Ideal Weight Checker Estimate ideal weight from the vet’s 9-point body condition score.