How old is your dog or cat in human years?
clear numbers, no fuss
The “7 years per year” rule is out of date: vets use size-based charts, because a Great Dane does not age at the pace of a chihuahua. This converter gives the human equivalent and the life stage — useful to adapt food, exercise and health checks.
In 2020, researchers proposed an “epigenetic clock” (16 × ln(age) + 31) showing that dogs age very fast in their first two years, then slow down. Vets still use the size-based chart in practice.
The charts we use
- Cats: 1 year = 15 human years, 2 years = 24, then + 4 human years per year — the feline life-stage chart (AAFP / ISFM).
- Dogs: the first year is worth about 13 to 15 human years depending on size, the second brings the total to 21–24, then + 4 (small), + 5 (medium), + 6 (large) or + 7 (giant) human years per year.
- Life stage: puppy or kitten, junior, adult, mature, senior — the bigger the dog, the earlier it becomes a senior (around 10 for a small dog, from 6 for a giant breed).
These equivalents are benchmarks to adapt care, not exact biological measures: breed, genetics and lifestyle all change how an animal really ages.
Pet age: straight answers
Is one dog year really seven human years?
No, that rule is out of date. The first year is worth about 15 human years, the second brings the total to around 24, then each year adds 4 to 7 years depending on size: large dogs age faster than small ones.
How old is a 2-year-old cat in human years?
About 24 human years. After that, each cat year adds about 4 human years: a 10-year-old cat is the equivalent of 56.
At what age is a dog a senior?
It depends on size: around 10 for a small dog, 8 for a medium dog, 7 for a large dog and from 6 for a giant breed. Becoming a senior is the time for a yearly, even six-monthly, vet check.
Are these equivalents scientific?
They are vets’ benchmark charts, based on physiological life stages. The epigenetic clock refines the curve, but the size-based chart remains the practical reference.
Keep exploring
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A shared pet health record
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Read the guides
Sources and benchmarks
Every life stage has its reminders
Vaccines, senior check-ups, worming: MyArk keeps track of health reminders and tells the whole household at the right time. Free on iPhone, no account needed.