Date Duration Calculator | Days Between Two Dates Free

Days Between Dates Calculator

This calculator finds the exact number of days, weeks, and the year-month-day span between two calendar dates. An Include End Date option adds one day to the count so both endpoints are included, and Countdown Mode switches to a live timer that counts down to a future date in days, hours, minutes, and seconds.

How the Duration Is Calculated

The total is the number of full days between the start and end date. The year-month-day breakdown works the way an age count does: it subtracts whole calendar years first, then whole calendar months from what is left, then reports the remaining days. Turning on Include End Date adds one day to the total, which matters for anything counted inclusively, such as a hotel stay or a work assignment that runs through its final day.

Example: Inclusive vs. Exclusive Count

A conference scheduled from March 3, 2025 to March 9, 2025 spans 6 days by default, since that is the gap between the two dates. Switching on Include End Date adds the closing day itself, bringing the total to 7 days, the figure most people mean when they call it a 7-day conference.

Example: Year-Month-Day Breakdown

Between January 1, 2025 and April 1, 2025, the calculator returns 90 days total, equal to 12.9 weeks, broken down as 3 months and 0 days. Extend the same start date to January 1, 2026, and the total becomes 365 days, or exactly 1 year.

Formula and Reference Table

The core calculation is a straightforward subtraction:

Total Days = End Date - Start Date
With Include End Date on: Total Days = (End Date - Start Date) + 1
Weeks = Total Days / 7

Reference values for spans starting January 1, 2025: