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Birthday Age Calculator
Calculate someone's age on a past or future date, the day of the week, and the number of days since their birth.
Age on that date
Choose both dates to calculate the age.
How to use this tool
Choose the details you know, review the result, and edit it until it sounds like you. Nothing you enter is sent to a server or saved by the tool.
Questions people ask
Can it calculate age on a future date?
Yes. Choose any target date on or after the birth date.
Does it store birth dates?
No. The calculation runs entirely in the browser.
How are leap-day birthdays handled?
In a non-leap year, the age increases on March 1. In a leap year, it increases on February 29. This is the calculator convention, rather than a rule for when to celebrate.
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