Date and time tools
Age Calculator
Calculate age in years, months, and days from a birth date locally in your browser.
Enter a birth date and an as-of date to see the age in years, months, and days. Dates are treated as UTC calendar days, so time zones do not change the result. Calculations run locally in your browser; your dates are not uploaded or stored.
Find an exact age without timezone surprises.
Enter a birth date and an as-of date to see the age in years, months, and days plus total days and full months. Dates are treated as UTC calendar days, so daylight-saving transitions do not change the result. Everything runs locally in your browser; your dates are not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
How does the age calculator work?
Enter a birth date and an as-of date. The calculator compares the two UTC calendar dates and reports the difference as full years, remaining months, and remaining days, plus total days and total full months.
What happens with leap-day birthdays or invalid dates?
Enter a real calendar date as YYYY-MM-DD; February 29 is accepted only in leap years. The calculator shows an error for invalid dates and when the birth date is after the as-of date.
Do time zones affect the result?
No. Both dates are treated as UTC calendar days, so daylight-saving transitions and local time zones do not change the result.
Do my dates stay private?
Yes. The calculation and copy action run locally in your browser. CodeASystem does not upload or store the dates you enter.