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Date & TimeFormula-based · Runs in your browser

Age Calculator

Find exact age, total days, and the next birthday from two dates.

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Inputs

Enter the values you know. Optional fields may be left empty.

Local save controls below
Required
Defaults to today

Result

Updates as valid inputs change.

Calculated locally
Exact age
—
Total days
—
Next birthday
—
Days until next birthday
—

Saved locally, explained clearly

Drafts, calculations, scenarios, and workflow progress stay in this browser unless you export them.

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Calculation steps

Follow what happened from the selected formula to the displayed answer.

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Calculate current inputs to see the working.
  1. 1

    Formula selected

    The calculator uses the following formula or method.

    Exact calendar difference = target date − birth date

    Month length and leap years are handled as calendar dates, not average day counts.

  2. 2

    Values entered

    Your values are placed into the calculation.

    Enter values to see what is used in this step.

  3. 3

    Result calculated

    The formula or method produces the following result values.

    Results will appear after a successful calculation.

  4. 4

    Answer formatted

    Displayed values are rounded and formatted using each output’s configured precision.

Scenario comparison

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Recent calculations

Successful calculations are retained locally according to your privacy settings.

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Data and privacy

How it works

The result counts complete years, then complete months, then remaining days. It uses real month lengths and leap years.

Input query strings and outputs

Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.

Input query strings

2
  • ?birthDate= Date of birth

    Date · Required · Default: 1990-01-01

  • ?targetDate= Age on date

    Date · Optional · Default: current date

Outputs

4
  • exactAge Exact age

    Text · Primary output

  • totalDays Total days

    Whole number

  • nextBirthday Next birthday

    Date

  • daysToBirthday Days until next birthday

    Whole number

Target date

The target date defaults to today in the browser. Change it to calculate age on a past or future date.

February 29

For a February 29 birth date, a non-leap-year birthday is clamped to the last day of February.

Sources
  • No external reference is listed for this calculator. Its formula and variable definitions are shown above.
Limitations
  • Month length and leap years are handled as calendar dates, not average day counts.
  • Calendar results depend on the selected dates and time-zone assumptions. Local holidays and daylight-saving changes are included only where stated.

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