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Age Calculator

Calculate exact age, days since birth, and days until the next birthday from a birth date and a reference date.

Overview

  • Calculates exact age in years, months, and days from a birth date and a reference date (usually today).
  • For a leap-day (February 29) birth date, the next birthday in a non-leap year is calculated as February 28.
  • Also shows the total number of days since birth and the number of days remaining until the next birthday.

Usage

  1. Enter a date into "Birth date".
  2. "Reference date" is automatically filled with today's date, but you can change it to any date.
  3. Click "Calculate" to display the exact age, days since birth, and days until the next birthday.

Example

Input

Birth date: 2000-01-15 / Reference date: 2026-09-18

Output

Age: 26y 8m 3d / Days since birth: 9743

Use Cases

  • Checking the exact age as of a specific date (such as for confirming an age requirement in some procedure)
  • Using the total number of days since birth as a reference when deciding on the timing of an anniversary or celebration
  • Checking how many days remain until the next birthday

FAQ

Can I set the reference date to a date in the past or future?

Yes. "Reference date" is initially filled with today's date, but you can change it to any date. Use this when you want to know the age as of a specific date.

How is the next birthday handled for someone born on February 29 (a leap day)?

If the year when February 29 would next occur is not a leap year, February 28 is used as the next birthday.

Is the birth date I enter sent anywhere?

No. The calculation runs entirely in your browser, and nothing is sent to an external server.

Notes

  • The birth date must be earlier than the reference date.
  • Only dates are handled; time of day (hours, minutes, seconds) is not considered.

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