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Time & Date

Age Calculator

Age Calculator

Calculate age in years, months, and days from a birth date.

Results update as you type.

How to use

Enter the birth date as YYYY-MM-DD. Optionally set an as-of date; leave it blank to use today. Read years, months, and days in the result panel.

Formula

Calendar difference from birth date to as-of date in years, months, and days (UTC date parts).

Worked example

  1. Born 2000-01-01 as of 2026-01-01 → 26 years, 0 months, 0 days.

Assumptions

  • Dates use year-month-day in the UTC calendar.
  • Leap days are handled by the calendar math, not by a 365.25-day average.
  • A birth date after the as-of date is rejected.

FAQs

Can I leave the as-of date blank?
Yes. The calculator uses today's date when the as-of field is empty.
What if the birth date is in the future?
Future birth dates are rejected. The as-of date must be on or after the birth date.
Does this use a 365-day year average?
No. It counts calendar years, months, and days, including leap days.
What format should I type?
Use YYYY-MM-DD, for example 2000-01-01.

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