Date Difference Calculator

This calculator finds the number of days between two dates, excluding both endpoints. To include both dates, add 1 to the result. Example: Jan 1 to Jan 3 = 2 days (difference), 3 days (inclusive).

In the D-day tab, select a target date and the calculator will automatically show how many days remain (D-N) or have passed (D+N) from today.

Yes, in the Date Diff tab, the calculator automatically shows the number of weekdays and weekend days (Sat & Sun) for the selected period.

In the Date Math tab, select a base date and enter the number of days to add or subtract. Example: January 1, 2026 + 100 days = April 11, 2026.

Yes, leap years (Feb 29) are automatically accounted for. A year is a leap year if divisible by 4, but not 100, unless also divisible by 400. 2024 and 2028 are leap years; 2025 and 2026 are not.

You can use the weekday count as an approximation of working days. Note that public holidays are not excluded, so for exact working days, subtract holidays manually.

Months are calculated by calendar. Jan 15 to Mar 15 is exactly 2 months. If days remain, the result shows 'N months M days'. Differences in month lengths (28–31 days) are automatically accounted for.