Days Between Dates Calculator

Choose a start date and an end date. The default calculation includes the start date and counts up to, but not including, the end date.

Turn on Include the end date when both selected dates should belong to the total. For example, the same start and end date changes from zero days to one counted day.

Use Swap dates to reverse the selected dates without retyping them. The calculator accepts either chronological direction.

The result shows total calendar days first, followed by Monday-to-Friday weekdays, weekend days, and an exact whole-weeks-plus-days breakdown.

The basic date difference is the number of civil calendar boundaries between the selected dates.

With the default end-date-excluded rule, July 11 to July 18 is seven calendar days. The counted dates are July 11 through July 17.

The result is based on calendar dates rather than elapsed clock hours, so crossing a daylight-saving change does not turn an adjacent pair of dates into zero or two calendar days.

Every date-range calculation needs a boundary rule. The most important question is whether the final date belongs to the count.

With the end date excluded, July 11 to July 18 equals seven days. Turning on end-date inclusion makes the same range eight days because July 18 is added.

When both selected dates are the same, the exclusive count is zero. Including the end date produces one counted day.

Neither convention is universally correct. Travel bookings, contracts, notices, subscriptions, employment rules, and project schedules can define their boundaries differently.

Calendar days include every date in the counted interval.

Weekdays count Monday through Friday. Weekend days count Saturday and Sunday.

A Monday-to-Friday count is sometimes described informally as business days or working days, but those terms can require additional rules. This calculator does not remove public holidays, regional holidays, observed holidays, or organization-specific closures.

Use the weekday result when you specifically need a weekend-only exclusion. Use a holiday-aware business-day calculator when non-working holidays must also be removed.

A weekday is a calendar classification: Monday, Tuesday, Wednesday, Thursday, or Friday.

A business day depends on context. A weekday may still be non-working because of a national holiday, regional holiday, bank holiday, company closure, or another rule.

That is why this calculator labels its result Weekdays rather than claiming that every Monday-to-Friday date is a valid business day.

A week always contains seven calendar days, so an exact week-and-day decomposition does not need an average.

For example, 17 calendar days equals two complete weeks plus three remaining days.

This is different from converting the interval into decimal weeks. The exact breakdown is usually easier to read when describing a schedule or elapsed date range.

Calendar months are not equal in length. They can contain 28, 29, 30, or 31 days.

Calendar years can contain 365 or 366 days. Because of those differences, a raw day count does not convert into an exact number of calendar months merely by division.

This calculator therefore labels its month and year outputs as average equivalents. It uses 365.2425 days per average Gregorian year and 30.436875 days per average month.

Use the exact calendar-day or week-and-day result when exact boundaries matter.

Gregorian leap years normally occur every four years, adding February 29.

Century years are exceptions unless they are divisible by 400. For example, 2000 was a leap year while 1900 was not.

The civil-date calculation applies those Gregorian rules directly, so intervals crossing February 29 are counted correctly without a separate leap-year setting.

The calculator treats each input as a civil calendar date rather than a local moment on a clock.

It converts each validated date to a Gregorian day number and performs arithmetic on those integer day values.

It does not calculate the number of milliseconds between two local-midnight JavaScript Date objects.

That matters around daylight-saving transitions because some local calendar days contain 23 or 25 elapsed hours. Two adjacent dates still remain one calendar day apart here.

The end date can be earlier than the start date. The calculation engine preserves that direction rather than rejecting the range.

The interface explains when the selected range runs backward while showing the magnitude of the calendar-day, weekday, weekend, and week breakdown for readability.

Boundary rules still apply to the selected direction. With the end date excluded, the start date belongs to the counted interval and the selected end date does not.

Use Swap dates when you simply entered the two dates in the opposite order.

A one-day difference is often caused by one calculator including the end date while another excludes it.

Larger differences can come from excluding weekends, public holidays, or both.

A duration calculator that includes times of day may also disagree with a date-only calculator because it measures elapsed hours instead of civil dates.

Before comparing results, check the start-date rule, end-date rule, weekend treatment, holiday treatment, calendar system, and whether times of day are involved.

The mathematically correct interval is not always the operational answer required by a real-world rule.

Before relying on a result, determine whether the start date counts, whether the end date counts, whether weekends are excluded, whether public holidays are excluded, and whether the deadline ends on a date or at a particular time.

For contracts, visas, employment notices, benefits, taxes, court filings, regulated deadlines, and similar matters, follow the governing document or applicable professional guidance rather than assuming a general date calculator defines the legal counting rule.