Leap day convention
For a birth date on February 29, the calculator uses February 28 as the birthday in non-leap years. This is a calculation convention, not a universal legal rule.
Date calculator
Age calculator
Calculate exact age from a birth date and a reference date without relying on time zones or daylight saving time.
Calculate an age
Method
Calendar age
age = complete years + complete months + remaining daysThe calculator counts complete calendar years, then complete calendar months, then the remaining days.
Total elapsed days
total days = reference day number - birth day numberDates are converted to Gregorian day numbers, so the result does not depend on local time or daylight saving time.
Examples
December 31, 2000 to July 15, 2026
Birth date = 2000-12-31, age on = 2026-07-15
Result = 25 years, 6 months and 15 days
February 29 in a non-leap year
Birth date = 2000-02-29, age on = 2025-02-28
Result = 25 years, 0 months and 0 days
Same date
Birth date = 2026-07-15, age on = 2026-07-15
Result = 0 years, 0 months and 0 days
Frequently asked questions
Does the calculator use my current time zone?
No. It compares calendar dates, not the exact local time of day.
How is February 29 handled?
In non-leap years, February 29 birthdays are treated as February 28 for this calculation convention.
Is this a legal age calculator?
No. Legal age rules can vary by country and context. This tool only applies a documented calendar convention.