How chronological age is calculated
Chronological age measures the calendar time elapsed between a person's birth date and a target date. The calculation accounts for the variable length of months and leap years.
Months are counted as full calendar increments from the day of birth. Any remaining days are calculated relative to the days in the preceding month.
Worked example
For someone born on 15 May 1990 calculating their age on 7 November 2026:
The calculator determines an exact age of 36 years, 5 months and 23 days. This corresponds to 437 total months or approximately 13,325 days lived, with 6 months and 8 days remaining until their 37th birthday.
Inputs for the age calculator
Date of birth
The calendar date on which you were born.
Age on date
The target calendar date at which you want to calculate your age, defaulting to today.
CALCULATOR QUESTIONS
Age calculator questions
How does the calculator handle leap years?
Leap years with 366 days (including 29 February) are accounted for using standard astronomical calendar arithmetic.
Can I calculate my age on a future date?
Yes, you can set the age on date to any future date to find out exactly how old you will be at a future milestone.