How the calculator estimates human age
Pets age much faster than humans in their first years and then slow down. We use a widely cited convention — communicated, among others, by the American Veterinary Medical Association (AVMA):
For dogs
- 1st year is roughly 15 human years.
- 2nd year adds +9 human years — a two-year-old dog is around 24 in human years.
- Each further year depends on size class:
- small (up to 10 kg): +4 years / year
- medium (10–25 kg): +5 years / year
- large (25–45 kg): +6 years / year
- giant (over 45 kg): +7 years / year
Smaller dog breeds usually have a longer life expectancy than very large ones. This is reflected in the human-age equivalent.
For cats
- 1st year is roughly 15 human years.
- 2nd year adds +9 human years — a two-year-old cat is around 24.
- Each further year adds about +4 human years.
Life stages — and what they mean
- Puppy / kitten (under 1 year): Growth phase. Primary vaccinations, gentle socialisation and the right nutrition lay the foundation for a long life.
- Junior (about 1–2 years): Physical and mental development is still ongoing. Patience, exercise and clear rules help.
- Adult (about 2–7 years): Stable life phase. Annual check-ups are usually enough.
- Senior (from about 7 years — earlier for giant breeds): Diseases of the kidneys, heart, joints or thyroid become more common. Half-yearly check-ups are recommended.
Why size matters in dogs
Giant breeds age faster than small ones. A Great Dane is clearly a senior at 7, while a Yorkshire Terrier often isn't until 9 or 10. The calculator reflects this through size classes.
What you can do as an owner
- regular check-ups — half-yearly for seniors,
- balanced diet and weight management,
- species- and age-appropriate exercise,
- dental care from day one,
- watch for behavioural changes and raise them early.
You can read more in our Senior dog and Senior cat guides.