Date calculator

How to count dates

Choose Days between for elapsed calendar days. By default, the start is day zero and the end is included. Select Include the start date too when counting every calendar date touched by an interval. Weekdays only uses the same endpoint choice but removes Saturdays and Sundays. Add or subtract days moves a date by a signed whole-day offset.

Worked example

Illustrative dates: from January 1, 2026 to January 8, 2026 is 7 elapsed days. Include the start date to count 8 dates. With the default endpoint rule there are 5 Monday–Friday days in that interval. Adding 30 calendar days to January 1, 2026 produces January 31, 2026. Enter a negative offset to move backward.

What this tool does not count

Weekday mode does not remove federal, state, school, bank, or employer holidays. It cannot interpret court rules, contract clauses, filing cutoffs, or local time-zone rules. Do not use its weekday total as an authoritative business deadline. Confirm any consequential date with the body responsible for it.

Calendar and date range

The tool uses the Gregorian calendar for years 0001–9999 and date-only arithmetic. It implements the Gregorian leap-year rule, including the century exception. It does not measure elapsed hours, so daylight-saving transitions do not change the number of calendar days. Earlier dates use a projected Gregorian calendar rather than historical local adoption rules. Months and years are intentionally not accepted as fixed numbers of days.