Age Calculator

Calculate exact age from date of birth with breakdowns by years, months, days, and upcoming birthday milestones.

Configure the reference window

All calculations happen instantly in the GMT

Birth date

Include time of day

Pick the calendar date you were born.

Reference

Switch to a custom reference to plan for eligibility checks, anniversaries, or future milestones.

Updating from the live clock every second.

Snapshot

TimezoneGMT

Reference—

Life stage—

Cycle progress—

Enter a valid birth date to calculate the age.

How the calculator works

This tool follows deterministic calendar math so every result is reproducible:

Chronological age is derived by subtracting the birth components from the reference and normalising seconds → minutes → hours → days → months → years. This honours real month lengths, leap years, and daylight saving shifts.
Birthday projections rebuild the original month, day, and optional time in the current year. If that date does not exist (for example 29 February on a non-leap year) it rolls to the last valid day to keep the countdown accurate.
Milestones are calculated by adding fixed day counts to the birth moment and comparing them to the reference. Everything runs in your browser, so no dates ever leave your device.

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