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Cat Age from Birth Date Calculator

Enter your cat's birth date to see its exact age, its age in human years and its life stage.

✔ Vet reviewed · 18 Oct 2026Updated 18 Oct 2026Sources: AAFP/AAHA · Vogt A.H. et al.
Cat Age from Birth Date CalculatorFree · instant
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Quick answer A cat born on 18 October 2016 is 10 years old on 18 October 2026, about 56 in human years and in the mature adult stage. A 1-year-old cat is about 15, a 2-year-old about 24, and each year after adds about 4.

How to use the cat age from birth date calculator

  1. Enter the birth date.
  2. Press Calculate.

Worked example

A cat born on 18 October 2016, checked on 18 October 2026.

Birth date
2016-10-18
On this date (leave empty for today)
2026-10-18
56 human years
Age
10 years
Life stage (AAFP/AAHA)
Mature adult

Human-year equivalents are estimates.

Example values are illustrative; this result is produced by the same calculator above.

How we calculate it

age (years) = days since birth ÷ 365.25; human years: year 1 = 15, year 2 = 24, then +4 per year; life stages: kitten <1, young adult 1–6, mature 7–10, senior >10

Sources: AAFP/AAHA · Vogt A.H. et al.

Understanding your result

Enter your cat's birth date and the calculator works out its exact age and converts it to human years using the AAFP/AAHA scale: 15 human years at 1 year, 24 at 2 years, then about 4 more each year.

It also shows the life stage: kitten under 1 year, young adult from 1 to 6, mature adult from 7 to 10 and senior over 10. A cat born on 18 October 2016 is 10 years old on 18 October 2026, about 56 in human years, and a mature adult.

If you do not know the birth date, ask your vet or the rescue for an estimate and use that date. The result is an estimate either way.

Common mistakes

  • Using the date you adopted the cat instead of its birth date.
  • Treating the human-year number as exact.
  • Using this for kittens under about a month; use the Puppy & Kitten Age Calculator.
  • Ignoring life stage when planning diet and check-ups.
  • Multiplying the age by seven.

Good to know

  • Senior cats benefit from regular check-ups; ask your vet how often.
  • Indoor and outdoor cats can age differently; the scale is an average.
  • The Cat Calorie Calculator helps you adjust food as your cat ages.

Frequently asked questions

How do I find my cat's age from its birth date?

Count the days from the birth date to today and divide by 365.25. The calculator converts the age to human years using the AAFP/AAHA life-stage scale.

What are the cat life stages?

Under 1 year is a kitten, 1–6 a young adult, 7–10 a mature adult and over 10 a senior.

Does it work for kittens under a month old?

Not for the human-year part. Use the Puppy & Kitten Age Calculator for the age in weeks and days of very young kittens.

Can I check the age on a different date?

Yes. Pick a date in the second box. Leave it empty to use today.

What if my cat is a rescue of unknown age?

Use your vet's estimate of the age and pick a birth date that gives it. The result is then an estimate.

Is this different from the Cat Age Calculator?

It starts from a birth date instead of an age you type in. Both use the same conversion.

Reviewed by a licensed veterinarian
Last reviewed 18 Oct 2026 · How we review

Sources

  1. AAFP/AAHA (2021) Feline Life Stage Guidelines
  2. Vogt A.H. et al. (2010) AAFP-AAHA Feline Life Stage Guidelines. Journal of Feline Medicine and Surgery 12:43–54

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Estimates only. Every pet is different — confirm with your veterinarian.