Every age, in human years
Pets
Dog and cat age conversion with the actual method stated — UCSD epigenetics for dogs, the accepted veterinary convention for cats.
Dog Age Calculator
Convert dog years to human years with the UCSD epigenetic formula or a size-based breed estimate.
Cat Age Calculator
Convert cat years to human years with the accepted veterinary convention (15 · +9 · +4).
Cat Pregnancy Calculator
Enter the mating date to see your cat’s estimated due date, the normal 58–72 day delivery window, how many days she is into the pregnancy and which stage she has reached.
Dog Pregnancy Calculator
Enter the mating date to see your dog’s estimated whelping date, the normal 58–68 day delivery window, how far along she is and the ultrasound and x-ray dates vets use to confirm the litter.
What this covers
Age conversion and gestation dates for dogs and cats, each with the actual method named on the page: the UC San Diego epigenetic formula for mixed-breed dogs, a size-based veterinary chart when a breed is chosen, the accepted 15 · +9 · +4 convention for cats, and published average gestation lengths for both species.
Which tool to use
Dog Age and Cat Age convert a pet’s age into human-equivalent years and a life stage. Dog Pregnancy and Cat Pregnancy work forward from a mating date to a due date and the normal delivery window — the dog page also marks the ultrasound and x-ray dates vets use to confirm a litter.
Frequently asked questions
Why is “multiply by seven” wrong for dogs?
Because ageing is not linear. A one-year-old dog is already closer to a young adult than to a seven-year-old child, and large breeds age faster than small ones. The UCSD formula and the size charts both reflect that.
Does breed change a gestation due date?
Not meaningfully. Gestation runs about the same length for every size in each species; breed predicts litter size far better than it predicts the date.
Can these replace a vet?
No. They are date and age arithmetic on published averages. Confirmation of a pregnancy, litter size and anything about an animal’s health needs a veterinarian.