Days Between Dates Calculator

To count the days between dates, subtract the start date from the end date. From 1 January to 31 December 2026 there are 364 days, or 365 if you count both dates. The calculator also shows weeks, months and business days, and works as a countdown when the start date is today.

By Editorial Team Updated 19 Oct 2026

How to use the date difference calculator

Pick the start date. It defaults to today, which turns the tool into a countdown.
Pick the end date. Choose any date in the past or future. If it is earlier than the start date the dates are swapped automatically.
Decide on the end date. Tick the box to count both the first and last day, for example for a holiday or a hotel booking period.

Including or excluding the end date

The most common source of off-by-one mistakes is whether the last day counts. By default the calculator gives the difference between the dates, which is what you want for deadlines, notice periods and “how long until”. Ticking “include the end date” adds one day, which is what you want when every day in the range is used, such as days of annual leave or the length of an event.

From	To	Excluding end date	Including end date
1 Jan 2026	31 Dec 2026	364 days	365 days
Mon 2 Mar 2026	Fri 6 Mar 2026	4 days	5 days
1 Jun 2026	1 Sep 2026	92 days	93 days

How many days until Christmas, holidays and deadlines

Leave the start date as today and pick the event date to get a countdown. On 17 October 2026 there are 69 days until Christmas Day: 9 weeks and 6 days, including 49 weekdays. Bookmark the page with your dates filled in, or use the Share button to send the countdown to someone else.

Using it as a business days calculator

Business days counts every Monday to Friday in the period. From Monday 2 March to Monday 9 March 2026 is 7 days but only 5 working days. Public holidays are not removed because they differ by country, state and region. Subtract them yourself: for example, England and Wales have 8 bank holidays a year and US federal employees have 11.

Legal and contractual deadlines sometimes have their own rules for counting days, such as excluding the day of service or rolling to the next working day. Check the rule that applies to you.

Months and years: the date duration calculator explained

Durations in months are less precise than days because months differ in length. The calculator counts whole calendar months first, then the remaining days. From 1 June to 1 September 2026 is exactly 3 months (92 days). From 31 January, one month later is treated as the last day of February.

For contracts and subscriptions, the number of days is the unambiguous figure; months and years are shown to make long periods easier to read.

Counting days by hand

Count the days left in the start month after the start date.
Add the full days of each month in between (31, 28 or 29, 31, 30, …).
Add the day number of the end date.

17 October to 25 December 2026: 14 days left in October + 30 in November + 25 in December = 69 days. Remember that February has 29 days in leap years such as 2028.

Days between dates FAQs

How many days are there in 2026?

365. 2026 is not a leap year. The next leap year is 2028, which has 366 days.

How many working days are in 2026?

There are 261 weekdays (Monday to Friday) in 2026, before public holidays are taken off.

Does the calculator handle leap years and daylight saving time?

Yes. It counts calendar days, so 29 February is included in leap years and clock changes do not create half-days.

How do I count days for a notice period?

Use the start of the notice as the start date and the last day of notice as the end date. Whether to include the end date depends on your contract wording.

Can I count backwards from a date?

Yes. Put the later date first and the earlier date second; the calculator swaps them and shows the difference.

Sources and methodology

Days are counted as whole calendar days between local dates, so daylight saving changes do not affect the result. Including the end date adds one day. Weekdays are Monday to Friday, without public holidays. Months are whole calendar months (clamped to month end) plus remaining days. All example figures were produced by this calculator.