Date & Time calculators
Find your age or count the days between two calendar dates.
Calculators in this category
2 toolsChoose the right calculator
Calendar age and elapsed days express time differently. Use age for completed years and months, and date difference for a calendar-day duration. Choose the reference date and counting convention before comparing results.
Age Calculator — Find completed years, months and remaining days between a birth date and a reference date, plus the total calendar-day count.
Date Difference Calculator — Count elapsed days between two dates, or include both endpoints. Equivalent weeks and hours are derived from the day count.
Before you calculate
Both tools use calendar dates normalized to UTC, rather than local timestamps. Weekends and holidays are included. Equivalent hours mean days multiplied by 24, so they do not represent a timezone-aware elapsed duration across daylight saving changes. Legal age rules may use different conventions.
A practical example
From February 28 to March 1 in leap year 2024, the elapsed difference is two days. Including both endpoints gives three calendar days. Review the Age tool's leap-birthday and month-end conventions when interpreting years, months and days.