CrateX.app

年齢計算機

生年月日から指定日までの正確な年齢を年・月・日と総日数で計算します。

Birth date

Use the calendar date, not a time of day.

As of date

Change this to calculate age on a past or future date.

The calculator compares calendar dates only, so timezone and time-of-day changes do not affect the result.

Result

年齢計算機

かんたんスタート

Enter the birth date, then choose the date you want to calculate age against.

Read the exact years-months-days age separately from total days; they answer different questions.

For enrollment dates, birthdays, or deadlines, change only the as-of date.

check how many full years, months, and days have passed.

see age on a past or future calendar date.

useful for records, planning, or rough day-count checks.

Dates are treated as calendar days, not timezone timestamps.

Total days uses the gap between dates; add one yourself if your workflow counts the start day.

If your browser does not show a date picker, enter dates as YYYY-MM-DD.

This tool does not interpret birth time, birthplace, timezones, or astrology-style rules.

Schools, exams, insurance, or legal age cutoffs can have their own inclusion rules.

Leap-day birthdays are calculated by calendar math; verify separately if an organization treats Feb 29 as Feb 28 or Mar 1.

Your dates are calculated in your browser and are not uploaded to a server.

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