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Date Difference Calculator

Find the number of days between two dates, plus years, months and days, total weeks, ISO week numbers and business days minus six countries' public holidays. How it works

Use the Date Difference Calculator

Duration
Pick a start and end date

Worked example

From January 30, 2025 to March 1, 2025 is 1 month and 1 day, or 30 days (31 with the end date included).

How it is counted: whole years first, then whole months, then days. A month is complete when the same day of the month is reached or, if that day does not exist in the month, on the month's last day, so January 30 to March 1, 2025 is 1 month and 1 day. A start date of February 29 reaches its yearly anniversary in a non-leap year on March 1, so February 29, 2024 to February 28, 2025 is 11 months and 30 days. Without "Include end date" the end date itself is not counted (October 2 to October 9 is 7 days); with it, one day is added to the counts (8 days) while the end date stays the one you chose. Hours, minutes and seconds are days × 24 and do not follow daylight-saving changes.

About the Date Difference Calculator

From October 8, 2026 to December 25, 2026 is 78 days: the end date minus the start date, with the end date itself not counted. This date difference calculator gives that count for any two dates, together with years, months and days, total weeks, and the working days in between, with the national holidays of six countries taken out if you pick one.

Days and weekdays in each quarter of 2026, and in a full year

PeriodStart dateEnd dateDays, end date not countedDays, end date countedWeekdays (Mon to Fri), end date counted
Q1 2026January 1, 2026March 31, 2026899064
Q2 2026April 1, 2026June 30, 2026909165
Q3 2026July 1, 2026September 30, 2026919266
Q4 2026October 1, 2026December 31, 2026919266
Year 2026January 1, 2026December 31, 2026364365261
Year 2027January 1, 2027December 31, 2027364365261
Year 2028 (leap year)January 1, 2028December 31, 2028365366260

Weekdays are Mondays to Fridays with no holidays removed. Pick a holiday country in the tool to take them out: 2026 has 250 working days with the US list and 253 with the UK list.

Month-end and leap-day cases

Start dateEnd dateYears, months and daysTotal daysISO 8601 duration
January 30, 2025March 1, 20251 month and 1 day30P1M1D
January 31, 2025February 28, 20251 month28P1M
January 31, 2025March 1, 20251 month and 1 day29P1M1D
January 31, 2024February 29, 20241 month29P1M
August 31, 2025September 30, 20251 month30P1M
February 29, 2024February 28, 202511 months and 30 days365P11M30D
February 29, 2024March 1, 20251 year366P1Y
December 25, 2025December 25, 20261 year365P1Y
October 2, 2026October 9, 20267 days7P7D

End date not counted. The third and last columns are what Copy gives as Natural language and as ISO 8601 duration.

How to use this tool

  1. Pick a start date and an end date, or tap a preset such as Last 30 days or Year to date.
  2. Tick Include end date if the last day should be counted too.
  3. Tick Business days to see the working days and the weekend days, and pick a holiday country (US, UK, Canada, Australia, Germany or France) to take its national holidays out.
  4. Use Copy to take the result as a sentence, an ISO 8601 duration, a number of days, or weeks and days.

Frequently asked questions

How many days are there between two dates?
Subtract the start date from the end date. From October 2 to October 9, 2026 is 7 days. With Include end date ticked it is 8, because the 2nd and the 9th are both counted.
How many days until Christmas 2026?
78 days from October 8, 2026 to December 25, 2026, of which 56 are weekdays. For the count from today, set the start date to today and the end date to December 25.
How many weekdays or business days are between two dates?
Tick Business days. The calculator counts the Mondays to Fridays in the range: the first quarter of 2026, January 1 through March 31 with the end date counted, has 64. Pick a holiday country to take its national holidays out: December 21 to 25, 2026, end date counted, is 5 weekdays and 4 US working days, because Christmas Day is the Friday. Regional holidays are not in the lists; the Working Days Calculator takes your own dates.
Does the count include the start date and the end date?
By default it runs from the start date up to the end date and stops there, the way nights are counted between two days. January 1 to December 31, 2026 is 364 days. Tick Include end date and it is 365.
How are months counted when they have different lengths?
A month is complete when the same day number comes round, or on the last day of a month that is too short. January 31 to February 28, 2025 is 1 month. January 31 to March 1, 2025 is 1 month and 1 day, or 29 days. A start date of February 29 reaches its yearly anniversary in a non-leap year on March 1, so February 29, 2024 to February 28, 2025 is 11 months and 30 days.
What are the ISO week numbers shown for each date?
The week of the year under ISO 8601: weeks start on Monday, and week 1 is the week that contains the year’s first Thursday. That is why January 1, 2027, a Friday, is shown as week 53 of 2026.

Deadlines, leases and billing periods

March 3 to April 2, 2026 is 30 days. A lease from June 1, 2026 to May 31, 2027 is 11 months and 30 days, or exactly 1 year with Include end date ticked; tick it whenever the first and the last day both count, as for an event from the 2nd through the 9th (8 days, not 7).

For a billing period, tick Business days and pick a Holiday country (US, UK, Canada, Australia, Germany or France) to take its national holidays out: December 21 to 25, 2026, end date included, is 5 weekdays but 4 US working days. For company closures or local holidays, the Working Days Calculator takes your own dates.

How the days are counted

Each date becomes a day number and the two are subtracted, so every leap day counts and a daylight-saving change cannot shift the result.

total days = day number of end date − day number of start date

Include end date adds one day. Full years come first, then full months, then leftover days. A month is full when the same day number comes round again, or on the last day of a month too short to have it: January 30, 2025 to March 1, 2025 is 1 month and 1 day, or 30 days (31 with the end date included). February 29, 2024 to February 28, 2025 is 11 months and 30 days.

  • Business days are Mondays to Fridays minus the chosen country's national holidays on a weekday (lists cover 1900 to 2200; regional holidays are not included).

  • Hours are total days × 24; minutes, × 1,440.

  • Week numbers follow ISO 8601.

  • Dates run from year 1 to year 9999; a link needs years 1000 to 9999.

Fun Fact: From January 1, 1996 to January 1, 2024 is 10,227 days, which is exactly 1,461 weeks. Both dates are Mondays: after 28 years with a leap day every fourth year, the dates land on the same weekdays again.

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