Date Difference Calculator

How to use this calculator

1. Enter a Start date and an End date.
2. Choose Days between dates for exclusive counting, or Include both start and end dates for inclusive counting.
3. Turn on Also show weekdays to add a Monday-to-Friday count alongside the calendar days.
4. The result updates as you type, showing the calendar days, the calendar-duration breakdown, whole weeks and approximate months. Use Reset to start again.

By default, the calculator shows days between the dates. Turn on "Include both dates" when you want to count every calendar date in the range. Either way, dates can be entered in any order — enter them in reverse and the calculator normalises them and shows a note.

This calculator compares calendar dates only. It ignores time of day, time zones, public holidays and local working-day rules.

What do I need to enter?

• Start date and End date — any two dates from 1 January 1900 to 31 December 2200, past or future, in either order.
• Count dates — Days between dates (exclusive) counts the day-steps from the start to the end; Include both start and end dates (inclusive) counts every date in the range, one more than exclusive.
• Also show weekdays (Monday to Friday) — optional. Adds a Monday-to-Friday count over the same range, without removing any holidays.

What do the results show?

• Calendar days — the main figure: the day count for the counting option you chose.
• Calendar duration — the exact gap as years, months and days, always from the earlier date to the later one.
• Whole weeks and Decimal weeks — the day count divided by 7, with leftover days shown beside the whole weeks.
• Approximate months and Approximate years — the day count divided by the average month or year length, labelled as approximate.
• Weekdays (Mon–Fri) — shown when the weekday option is on.
• Date breakdown — a table of both dates with their weekdays and every figure above.

How is the number of days between two dates calculated?

The calculator counts real calendar days from one date to the other — it never converts either date into a timestamp or subtracts 24-hour periods, so the result cannot be thrown off by a daylight-saving clock change or a time zone.

Example: 1 March to 2 March is 1 day exclusive, or 2 days inclusive. Over a longer span, 15 January 2026 to 30 March 2026 is 74 days exclusive (75 inclusive), which is 10 whole weeks and 4 days, and a calendar duration of 2 months and 15 days.

What is the difference between inclusive and exclusive counting?

Exclusive counting — the default — treats the two dates as the ends of a range and counts the steps between them, the way you would count nights on a booking. Inclusive counting counts every calendar date in the range, including both the start and the end date, which is one more than the exclusive count. Neither figure changes the calendar-duration breakdown (years, months and days), which is always the exact interval from the earlier date to the later one.

Why does the calendar duration differ from the approximate months and years?

The calendar duration works through years, months and days the way a calendar does — it counts whole months from the start date, using each month's real length, then the leftover days. The approximate months and years instead divide the total day count by the average length of a Gregorian month (30.436875 days) or year (365.2425 days). Both are useful figures, but they answer different questions: the calendar duration matches "how a person would describe the gap", while the approximate figures are a quick day-count conversion. They are labelled separately so the two are never confused.

How are weeks between two dates calculated?

Whole weeks are the selected day count divided by 7 and rounded down, with the leftover days shown alongside — for example, 74 days is 10 whole weeks and 4 remaining days. The decimal weeks figure is the same day count divided by 7 without rounding, so 74 days is also 10.57 weeks.

How does the weekday count work?

Turning on "Also show weekdays" counts Monday to Friday only, over the same exclusive or inclusive range as the day count. Monday to Tuesday is 1 weekday exclusive, or 2 inclusive; Friday to the following Monday is 1 weekday exclusive (Friday itself), or 2 inclusive (Friday and Monday). This is a plain weekday count — it does not subtract public holidays, bank holidays, company holidays or any other local non-working day, so it is not the same as a business-day or working-day calculation.

What happens if I enter the end date before the start date?

The calculator still works. It keeps the two dates you entered exactly as typed, shows a note that they were entered in reverse chronological order, and calculates the duration from the earlier date to the later one as a positive number of days, weeks, months and years. This version does not show a signed (negative) difference or an "add or subtract days" mode.

What this calculator does not do

• It ignores time of day and time zones — only the calendar date matters.
• It does not remove public holidays, bank holidays or company holidays from the weekday count.
• It is not a legal, payroll, contractual-deadline or visa calculator — those often have their own counting rules, cut-off times and exclusions.
• It does not add or subtract a number of days from a single date, and does not repeat on a schedule.
• Approximate months and years are clearly labelled and are not the calendar duration.

Is my data private?

Yes. The calculation runs entirely in your browser using the dates you enter. Nothing is sent to a server, no calendar is connected, and no date, duration or weekday value you enter is recorded in analytics.

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Frequently asked questions