Free online cat age calculator

How to use

1. Click Cat to Human or Human to Cat depending on what you want to convert.
2. Enter the age in years.
3. Click Calculate.
4. Read the equivalent age and the cat’s life stage.

Formula

Cat → Human
  age < 1 yr:   human age = cat age × 15
  age = 1 yr:   human age = 15
  1 < age < 2:  human age = 15 + (cat age − 1) × 9
  age ≥ 2:      human age = 24 + (cat age − 2) × 4

Human → Cat (inverse)
  human < 15:   cat age = human age / 15
  15 ≤ human < 24: cat age = 1 + (human age − 15) / 9
  human ≥ 24:   cat age = 2 + (human age − 24) / 4

Life stages:
  Kitten:    0–1 yr
  Junior:    1–2 yr
  Prime:     3–6 yr
  Mature:    7–10 yr
  Senior:    11–14 yr
  Geriatric: 15+ yr

Worked example

5-year-old cat:

human age = 24 + (5 − 2) × 4
          = 24 + 12
          = 36 human years
life stage = Prime

Notes

• Cat age conversion is an approximation. Individual cats age at different rates depending on breed, diet, indoor versus outdoor lifestyle, and veterinary care.
• Consult your vet for a health assessment rather than relying solely on age equivalency.