Calculator guide
Calculate calendar age from a date of birth to a target date, including completed years, months, and days.
Formula or method
Age is the calendar difference between birth date and target date, borrowing days and months as needed rather than dividing days by 365.
How to use this calculator
- Enter date of birth.
- Enter the target date or use today.
- Review completed years, months, and days and check the dates.
Worked example
Someone born June 15, 1990 is 33 years, 8 months, and 16 days old on March 1, 2024.
Understanding the result
Calendar age counts anniversaries; an approximate age in days is a different measure.
Limitations and assumptions
- A future birth date is not a valid age scenario.
- Time of birth and time zones are ignored for date-only results.
Frequently asked questions
Why is age not days divided by 365?
Leap years and calendar month lengths make that shortcut approximate.
Can I calculate age on a past date?
Yes, enter that date as the target if it is on or after birth.
Does this determine legal age?
Legal thresholds and jurisdictions may use specific rules; verify the applicable law.
Sources
Educational information only; verify important decisions with a qualified professional.