Detailed guide
How to use the age calculator
Calculate an exact age
Everyday age normally means completed years. A precise interval also includes the months and days since the last birthday. The calculator presents all three components and the total number of calendar days between birth and the reference date.
Today is selected by default, but any later reference date can be used to find an age at a past event or planned future date. A date before the birth date is not a valid reference.
Why months are not converted to thirty days
A calendar month has no fixed duration. February and months with 30 or 31 days would make a flat conversion inaccurate. The tool therefore calculates a real calendar interval between the two dates.
Leap years are included automatically, including births on February 29. The legal treatment of that birthday in a non-leap year can depend on the country and purpose.
When a reference-date age is useful
Reference ages are used for anniversaries, insurance overviews, sport categories, school or care dates and travel planning. Official decisions can additionally depend on a specific statutory definition of the cutoff date.
The calculator does not create a user account or permanent profile for the date of birth. Inputs can form part of the requested URL and may therefore appear in browser history, referrers or technically necessary server logs. Official documents and the applicable cutoff rule remain decisive for administrative purposes.