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Age Calculator

Calculate your exact age in years, months, and days from your date of birth. Handles Feb-29 birthdays and shows your next birthday.

Birthday
Your age
36
years old
5 months 13 days
13,313 days lived
Next birthday: January 1, 2027

About This Calculator

Enter your date of birth to see your exact age in years, months, and days, plus the total number of days you have lived. Feb-29 birthdays are celebrated on Feb-28 in non-leap years (the convention used in most jurisdictions).

How It Works

The calculator finds the number of completed years since your birthday, then the remaining months and days. All arithmetic uses UTC calendar dates to avoid any daylight saving ambiguity.

The Formula

Age = completed years since birthday. For Feb-29 birthdays in non-leap years, the effective anniversary is Feb-28 (locale-dependent: UK law uses Mar-1, but this calculator defaults to Feb-28). Total days = JDN(today) − JDN(birthday).

Frequently Asked Questions

What happens to Feb-29 birthdays in non-leap years?
Most countries treat Feb-28 as the legal birthday in non-leap years. A few (like the UK) use Mar-1. This calculator defaults to Feb-28 — you officially turn another year older on Feb-28.
Why does my age show as one year less than expected?
If your birthday hasn't occurred yet this calendar year, you haven't completed that year yet. Age = completed years, not the current year minus birth year.