About

Calculating age requires more than simply subtracting the birth year from the current year. Leap years, varying month lengths, and time zones complicate manual calculations. This tool provides a precise breakdown of chronological age based on the Gregorian calendar system.

Legal, medical, and administrative processes often demand age precision down to the day. For example, eligibility for specific insurance policies or retirement benefits triggers on an exact date. This calculator accounts for leap year anomalies to deliver an accurate duration from the date of birth to the present moment.

Formulas

The core logic computes the difference between the current timestamp t_now and the birth timestamp t_birth.

Age = t_now − t_birth

This difference in milliseconds is then converted into larger units using modular arithmetic to handle the varying number of days in months.

Reference Data

Time Unit	Average Duration	Notes
Year	365.2425 days	Accounts for Leap Years
Month	30.44 days	Average across 12 months
Week	7 days	Constant
Day	24 hours	Standard Earth rotation
Hour	60 minutes	Base 60 system
Minute	60 seconds	Base 60 system

Frequently Asked Questions

The calculator uses the native Date object methods which internally account for the extra day in February every four years (with century exceptions).

Yes. The results breakdown includes a "Total Weeks" metric, which is useful for tracking pregnancy or infant development stages.

Months vary between 28, 29, 30, and 31 days. The calculator strictly follows the calendar days rather than using a 30-day average for the precise output.

Dates are calculated based on the local time of your browser. If you were born in a different time zone, the "hours" precision might vary slightly.