Pet Age Calculator

How to use

1. 1Pick Dog or Cat at the top.
2. 2Enter your pet's age in years. Add extra months for puppy and kitten precision.
3. 3For dogs, pick the adult size category (small, medium, large, or giant). Type an adult weight in kg or lb and tap the suggestion to auto-pick the matching size.
4. 4Choose the calculation method you want as the headline (size-based AAHA, 2019 epigenetic, or classic for dogs; AAHA ladder or classic for cats). Every method is also shown side by side.
5. 5Read the human-equivalent age, the life-stage badge, and the comparison list. Use Copy on any row or Copy summary to share the full breakdown.

About this tool

Pet Age Calculator converts a dog or cat's age into a human-equivalent age using the methods veterinarians actually use, with three formulas for dogs and two for cats so you can compare them on the same input. The dog size-based table follows the American Animal Hospital Association schedule: year 1 counts as 15 human years, year 2 adds another 9 (so a 2 year old dog is roughly 24 in human terms), and each year after that adds between 4 and 7 human years depending on adult body weight (small up to 9 kg / 20 lb is 4, medium 9 to 23 kg / 20 to 50 lb is 5, large 23 to 45 kg / 50 to 99 lb is 6, giant over 45 kg / 99 lb is 7). The 2019 epigenetic clock published by Wang and colleagues (16 x ln(dog age) + 31) draws on DNA methylation research and is included for comparison; under one year it falls back to a linear ramp because the logarithmic formula was calibrated on adult dogs. The classic 7 years rule is included as a reference because everyone knows it, but it is also clearly labelled as inaccurate, especially for the first two years and for small breeds. For cats the tool uses the AAHA / AAFP feline life-stage ladder (15 at year 1, 24 at year 2, then 4 per year), with a simpler classic comparator. Every method is shown side by side so you can read off all of them at once, and a life-stage badge (Puppy, Junior, Adult, Mature, Senior, Geriatric for dogs; Kitten, Junior, Adult, Mature, Senior, Super Senior for cats) summarises what the vet care plan looks like at this point in your pet's life. Optional adult weight in kg or lb suggests the matching dog size category in one click, age accepts whole years plus extra months for puppy and kitten precision, and a copy summary captures the headline and every comparison so you can paste it into a note or share it with your vet. Useful for new dog and cat owners trying to understand what life stage their pet is in, owners of senior pets deciding whether to switch to twice-yearly wellness exams, breed owners comparing how the same age means different things for a Chihuahua and a Mastiff, and anyone curious how the classic 'multiply by 7' rule compares to the modern AAHA and epigenetic methods. Calculations run entirely in your browser, so the ages and weights you type here stay on your device. These are estimates from population research, not a medical assessment; talk to a veterinarian for an accurate life-stage and health evaluation for your individual pet.

Free to use. Works in your browser. No signup, no login.