How to use the Age Calculator
- Enter the birth date using the calendar control.
- Choose today or another date on which you want to measure age.
- Read the calendar age, completed months, elapsed days, and time until the next birthday.
How the calculation works
Age = target date − birth date, adjusted for incomplete months and daysThe calculation first finds the calendar-year difference, then borrows from prior months when the target day has not reached the birth day. Total days are calculated independently from UTC calendar dates.
Example calculation
A person born on January 1, 1990 is 36 years, 7 months, and 24 days old on August 25, 2026. The calendar components reflect month lengths rather than treating every month as 30 days.
How to interpret the result
Calendar age is best for birthdays and official age questions. Total days is better for elapsed-time comparisons because it represents one continuous count.
Notes and assumptions
- Both inputs are treated as calendar dates, without time-of-day or timezone conversion.
- The target date must be on or after the birth date.
- For February 29 birthdays, the next birthday follows the valid calendar date in the target year.
Age Calculator questions
Why is age not just days divided by 365?
Years include different numbers of days because of leap years, and calendar months have different lengths.
Can I calculate age on a future date?
Yes. Select any target date after the date of birth.
Does the calculator account for leap years?
Yes. It uses real calendar dates, including February 29 where applicable.