Date Difference Calculator

How do you calculate the days between two dates?

Enter the start and end dates to calculate their absolute calendar difference. The default rule includes the earlier date and excludes the later date. For example, Monday to the following Monday is seven calendar days. The results also show complete weeks with leftover days, a calendar breakdown in years, months and days, and conversions to hours and minutes. Use the Today buttons when one boundary should be the current local date.

For a worked example, choose a Monday as Start date and the following Monday as End date. Leave the default endpoints and Saturday–Sunday weekend, then enter that Wednesday as a holiday. The counted interval runs from the first Monday through Sunday. The result is seven calendar days, one week, 168 hours, 10,080 minutes and four business days. Expand Counted days to verify 7 calendar days − 2 non-working weekdays − 1 working-day holiday = 4 business days.

Input order does not change the size of the result. If the end date precedes the start date, the calculator identifies that order and still shows a positive difference. The boundary switches always refer to the earlier and later dates chronologically. This keeps the counting convention stable when you swap the two fields. For an age expressed in calendar units, the related age calculator provides a more focused workflow.

When should you include the first and last days?

Boundary rules matter when a range describes attendance, leave, bookings or a deadline. A Monday-through-Friday attendance period contains five dates if both endpoints count. The same inputs produce four days under the default elapsed-date convention. Excluding both endpoints counts only Tuesday, Wednesday and Thursday. Including only the later endpoint counts Tuesday through Friday. Although the two four-day options have equal calendar totals, their business-day totals can differ when a boundary falls on a weekend or holiday.

All displayed totals use the selected boundaries. The calendar breakdown also uses the first counted date and the boundary immediately after the last counted date. On a same-date range, including both endpoints counts one day, while the other combinations count zero. For a contractual deadline, choose the rule stated in the agreement rather than assuming that every process uses the same convention.

How can you customize business days for your schedule?

Business days are the counted dates remaining after your non-working weekdays and entered holidays are removed. Saturday and Sunday are selected initially. Change those selections for a Friday–Saturday weekend, a six-day working week or a personal part-time schedule. Clearing all seven selections makes every weekday eligible; selecting all seven produces zero business days. These settings change business days without changing calendar-day totals.

Enter holidays or personal days off in ISO date format, with one date per line or separators such as commas. A repeated holiday is deducted only once. A date already excluded by the weekday selection is not deducted again, and a date outside the counted interval has no effect. Invalid entries display an error and suppress results so a mistyped holiday cannot silently change your answer. There is no automatic country calendar: maintain your own list for the location and organization involved.

Which holiday calendar files can you import?

Use Import holiday calendar (.ics) to read a local file on your device. The importer accepts all-day events with date-only values and simple annual repeats written as FREQ=YEARLY without additional rule options. Multi-day events use an exclusive end date: an event starting Monday and ending Thursday contributes Monday, Tuesday and Wednesday. Accepted event durations range from one to 366 days; files larger than 1,000,000 bytes are rejected.

This is a holiday importer rather than a complete calendar application. Timed appointments, more complex recurrence rules, and events using EXDATE, RDATE or DURATION are skipped. Review the unsupported-event count after import and add missing holiday dates manually. The imported list shows event dates and names, with Remove controls for unwanted days. No country holidays or substitute observance dates are supplied automatically.

How do you add or subtract business days?

Select Add / subtract business days when you know a starting date and a number of working days rather than two endpoints. Enter a whole number in Business days to add or subtract: positive moves forward, negative moves backward, and zero returns the start date unchanged. Counting begins on the next or previous calendar date, so the start itself is never consumed as a business day. Manual and imported holidays are shared with the date-difference mode.

Choose Saturday–Sunday weekend, Friday–Saturday weekend or Sunday only weekend in Weekend definition. This selection is separate from the customizable weekday checkboxes in Date difference. Starting on a Friday and adding one with Saturday–Sunday selected returns Monday; if that Monday is in your holiday list, it returns Tuesday. Endpoint inclusion switches do not apply here. Fractional amounts or calculations that leave the supported date range do not produce a result.

Why does the calendar breakdown differ from total days?

Months have different lengths, so dividing a day count by a fixed number cannot give an exact calendar-month difference. This calculator counts whole months anchored to the first counted date, then groups every twelve months into a year. When the starting day does not exist in the target month, it uses that month's last day. January 31 to March 31 is two complete months; January 31 to March 1 is one complete month plus the remaining days after February's last day.

Leap days follow Gregorian calendar rules. February has twenty-nine days in a leap year and twenty-eight otherwise. Total days reflect that difference automatically. Month-end clamping is an explicit convention, so compare its definition with any external system before transferring a calendar breakdown. Total days provide a direct measure of the selected interval without requiring an interpretation of the word month.

What do the copied report and time totals contain?

Copy an individual total for a spreadsheet cell, or copy the full report when the assumptions need to travel with the answer. The report includes the original dates, calendar breakdown, calendar totals, business-day total, endpoint settings, selected non-working weekdays, entered holiday list and the number of working-day holidays actually deducted. This makes a copied result easier to review later than a bare number.

Hours and minutes are conversions using twenty-four hours per counted day and sixty minutes per hour. They do not measure elapsed local clock time through daylight saving transitions. For clock-time comparisons, use the time zone converter. For timestamp work, use the Unix timestamp converter and account for the relevant time zone. This date calculator accepts four-digit years starting at 0001 and ending at 9999; long ranges use whole-week arithmetic for business days instead of a loop over every date.