--- title: "Date Duration Calculator" type: "page" canonical_url: "https://simcalculo.com/en/date-duration-calculator/" markdown_url: "https://simcalculo.com/en/date-duration-calculator.md" date_published: "2026-10-20T00:47:04-03:00" date_modified: "2026-10-20T00:47:04-03:00" author: "" language: "en-US" category: "" summary: "How to calculate days between two dates Enter a start date and an end date, then select Calculate duration. The main result is the number of calendar days. You also get complete weeks plus remaining days, a calendar breakdown in years, months and days, and…" --- # Date Duration Calculator ## Date Duration Calculator Count calendar days between two dates. See weeks and days, calendar years and months, and an optional Monday–Friday count. ### Choose your dates Start dateEnd date Use the date picker. The date input format follows your browser settings; results use month names. Dates from 1900 through 2099 are supported. Show weekdays (Mon–Fri)Include end date By default, the start date is included and the end date is excluded. Including the end date adds one calendar day. This is a date-only calculation, with no times of day. Calculate durationUse exampleClear Calendar days**** #### Weeks and days **** #### Calendar duration **** #### Weekdays (Mon–Fri) **** #### Weekend days **** Your dates were in reverse order. The calculator used the earlier date as the start. Calendar years and months are counted in order, with month-end dates clamped to the last valid day. Months are not treated as fixed 30-day periods. Copy result Your dates are calculated in this browser. This calculator does not send your dates to our server, save them in browser storage or transfer them when you change language. ## How to calculate days between two dates Enter a start date and an end date, then select Calculate duration. The main result is the number of calendar days. You also get complete weeks plus remaining days, a calendar breakdown in years, months and days, and an optional count of weekdays from Monday through Friday. Use the calendar controls. Their input format follows your browser settings; the result spells out the month to avoid day/month ambiguity. The calculator accepts dates from January 1, 1900 through December 31, 2099. It uses Gregorian calendar dates without times of day and calculates in UTC to avoid daylight-saving changes affecting the day count. ## Is the end date included? By default, the interval includes the start date and excludes the end date. March 1 to March 8, 2026 is 7 calendar days. Select Include end date to count March 8 as well, giving 8 days. If both fields contain the same date, the result is zero days by default or one day when the end date is included. The same endpoint rule applies to the optional weekday count: including a Saturday or Sunday adds one calendar day and no weekday. ## Weeks and days versus calendar months Complete weeks = floor(calendar days ÷ 7). Remaining days = calendar days modulo 7. For example, 10 days is 1 week and 3 days. This does not depend on the day of the week on which the interval begins. The year/month/day breakdown uses actual calendar boundaries, not fixed 30-day months or 365-day years. It counts complete years from the earlier date, then complete months, then remaining days. If an anniversary would fall beyond the end of a month, it uses that month’s last valid day. For example, January 31 to February 28, 2026 is 28 days or 1 calendar month under this rule. For an inclusive end date, the calendar breakdown is calculated through the day after the entered end date. Calendar-duration conventions can differ between software, especially around month ends; this page states the convention used here. ## How the Monday–Friday count works Select Show weekdays (Mon–Fri) to count eligible days in the same interval. Saturdays and Sundays are excluded. From Monday, October 19 to Saturday, October 24, 2026, with the end excluded, there are 5 weekdays. Including that Saturday still gives 5 weekdays. The default tool does not deduct public holidays, infer your country or follow shift patterns. Its weekday result is not a holiday-aware working-day or legal-deadline calculation. If your deadline uses different inclusion rules or a specific work calendar, check those rules separately. ## What if the dates are reversed? The calculator places the earlier date first, returns a nonnegative duration and displays a notice when it has reordered your inputs. It does not return a negative elapsed time or automatically use today’s date. Both dates must be entered. ## Example: a full week For March 1 to March 8, 2026 with the end excluded, the result is 7 days, or 1 week and 0 days. The interval contains 5 weekdays and 2 weekend days. Including March 8 adds a Sunday, giving 8 days, 5 weekdays and 3 weekend days. ## Privacy and language The calculation runs in your browser. This calculator does not send the entered dates to our server, save them in browser storage or place them in the page address. Copy result copies the dates and result to your device’s clipboard only when you select that button. The [Portuguese day counter](https://simcalculo.com/pt-br/contador-de-dias-entre-datas/) uses the same calculation code. Labels, date displays and explanations are localized. The language switch opens the equivalent page without transferring your entered dates.