Everyday calculators

Age Calculator

Calculate an exact calendar age on any date, elapsed days and weeks, the birth weekday, and the next birthday without timezone drift.

Calendar dates

Calculate age on a date

Date-only calculation

Calendar dates are compared at UTC midnight. Time of birth, current clock time, and daylight-saving changes do not alter the result.

Choose two valid dates

Your exact calendar age and next birthday will appear here.

Calendar aid only. Legal age rules—especially for February 29 births—can vary by jurisdiction and purpose.

How to use it

Get a reliable result

  1. Enter the date of birth.
  2. Choose the date on which age should be measured or select Use today.
  3. Review the exact calendar age, elapsed totals, birth weekday, and next birthday, then copy the summary if needed.

Useful for

Common workflows

  • Find an exact age for a form or personal record
  • Count the days or weeks elapsed since a birth date
  • Plan for the next birthday or compare age on a past date

Examples

What to expect

Exact calendar age
Input
January 15, 1990 through August 29, 2026
Output
36 years, 7 months, and 14 days
Leap-day birth
Input
February 29, 2000 through February 28, 2025
Output
25 years using this tool's February 28 non-leap-year convention

Legal treatment of February 29 birthdays varies by jurisdiction and purpose.

Know before you start

Important limitations

  • The calculation uses calendar dates only and does not consider time of birth, current clock time, or fractional days.
  • February 29 anniversaries use February 28 in non-leap years; legal or administrative rules can use a different convention.
  • Completed months use clamped calendar anniversaries, so month-end births can produce results that differ from systems using average month lengths.
  • The tool accepts years 0001 through 9999 and does not model historical calendar reforms before adoption of the modern Gregorian calendar.
  • Results are a calendar aid and should not replace official legal, medical, benefits, or eligibility determinations.

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Common questions

Age Calculator FAQ

How are years, months, and days calculated?

The calculator subtracts complete calendar years first, complete calendar months from that anniversary next, and then counts the remaining whole UTC date boundaries.

How are February 29 birthdays handled?

For a non-leap year, Tool Packer uses February 28 as the birthday anniversary. This is a stated calculation convention, not a claim about legal age rules everywhere.

Why use UTC for a date-only calculation?

UTC midnight gives every calendar date one stable value. That prevents daylight-saving changes or the browser's local offset from adding or removing a day.

Are birth dates uploaded?

No. Date parsing, calendar arithmetic, formatting, and clipboard output remain in the current browser.

Browser-local

Processed on your device

Birth dates, comparison dates, and calculated results stay in this browser and are never uploaded or stored.

How this processing works

The tool reads and processes this input in your browser. Tool Packer's application server does not receive the input or generated result.

Read the full privacy explanation