Enter your birth date and time, including seconds, in the format selected in the site settings. US uses a 12-hour time with AM or PM; EU and ISO use a 24-hour time. Changing the format keeps the same birth date and time.
The birth timezone identifies when you were born. The calculation timezone determines the calendar used for your age at the current moment. Both initially use the timezone selected in the site settings and can be changed independently.
The result updates automatically in years, months, weeks, days, hours, minutes and seconds. Years and months use calendar arithmetic; weeks are seven calendar days. Daylight-saving changes can affect the remaining hours. A future or invalid birth time shows an error.
Display copies a link to a read-only age view that updates automatically. It shows the SundyMondy logo, My age now caption, live age, a link back to the Age tab and the standard legal footer. Share copies a link containing the birth details and both timezones. Anyone with that link can read those details. Verify critical dates before relying on the result.
Worked example
A person born on January 1, 2000 at 00:00:00 UTC is exactly 26 years old on January 1, 2026 at 00:00:00 UTC when the calculation timezone is UTC.
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