How to use Age Calculator
Enter a birth date and the date on which you want to know the age. The result separates complete years, remaining calendar months and remaining days. It also shows elapsed days and complete weeks, which answer a different question from calendar age.
Calendar months have different lengths. This tool treats an anniversary that does not exist in a shorter month as the last day of that month. For example, a 29 February birthday is clamped to 28 February in a non-leap year. Legal age conventions can differ by jurisdiction.
The formula
A worked example
Date of birth: 2000-01-15 · Age on this date: 2026-10-07
Age on the reference date: 26 years, 8 months, 22 days
Uses UTC calendar dates. For a missing day in a shorter month, the anniversary is clamped to that month’s last day.
Questions about this calculation
Are leap years included?
Yes. The elapsed-day calculation uses the Gregorian calendar, including leap days.
Is my birth date sent to a server?
The calculator runs in your browser. Sharing the result does not include your birth date.
Formula checks: 2026-10-08. Assumptions & corrections.