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Counting the days between two dates sounds simple, until you need to decide whether to include the first and last day, skip weekends or account for bank holidays. Small differences in how you count can matter for deadlines, notice periods, holidays and contracts.

This guide explains how to count calendar days and working days in the UK. To do it instantly, use the days between dates calculator.

Calendar days

The simplest count is calendar days: every day, including weekends and holidays.

Inclusive or exclusive?

There are two common ways to count:

• Exclusive (the usual way): count the days from one date to the other, not including the end date. From Monday to Wednesday is 2 days.
• Inclusive: count both the start and end dates. From Monday to Wednesday is 3 days.

Use inclusive counting when you want the number of days something lasts, such as a holiday from Monday to Wednesday, where you're away for three days. Use exclusive counting for the gap between two dates, such as how many days until an event. The calculator lets you choose.

Working days

Working days, also called business days, are usually Monday to Friday, excluding bank holidays. They're used for things like delivery times, payment terms and many legal and HR deadlines.

To count working days:

1. Count the calendar days in the period.
2. Remove Saturdays and Sundays.
3. Remove any bank holidays that fall on weekdays.

For example, from Tuesday 22 December 2026 to Saturday 2 January 2027 inclusive is 12 calendar days. Removing three weekend days and three bank holidays (Christmas Day, the Boxing Day substitute on Monday 28 December, and New Year's Day) leaves 6 working days.

UK bank holidays

The UK has different bank holidays in each nation:

In England and Wales, they are New Year's Day, Good Friday, Easter Monday, the Early May bank holiday, the Spring bank holiday, the Summer bank holiday, Christmas Day and Boxing Day.

Substitute days

When a bank holiday falls on a weekend, a substitute day is usually given on the following weekday. For example, if Boxing Day falls on a Saturday, the substitute is the following Monday.

One-off bank holidays

Occasionally, extra bank holidays are added for national events, such as the 2022 Platinum Jubilee and the 2023 Coronation, or existing ones are moved. The calculator includes the known one-off changes for England and Wales.

Adding working days to a date

Many deadlines are set as a number of working days after an event, for example "within 10 working days". To work it out, count forward one day at a time, skipping weekends and bank holidays.

Adding 10 working days to Friday 18 December 2026 lands on Wednesday 6 January 2027, because Christmas, the Boxing Day substitute and New Year's Day are all skipped. The calculator's "add days" mode does this automatically.

Common uses

• Notice periods. Employment contracts often state notice in weeks. Statutory minimum notice from an employer is one week for each full year worked, up to 12 weeks, after the first month.
• Holiday planning. Count how many working days of leave a trip uses. Our holiday entitlement calculator shows your yearly allowance.
• Invoices and payment terms. "30 days" usually means calendar days unless the contract says working days.
• Deadlines and countdowns. How many days until a wedding, exam or due date.
• Pregnancy. Our pregnancy due date calculator counts weeks from your last period.

Tips for avoiding mistakes

1. Check whether the deadline uses calendar or working days.
2. Check whether the count is inclusive or exclusive.
3. Use the right nation's bank holidays.
4. Watch for leap years: February has 29 days in years like 2028.
5. If a deadline falls on a weekend or bank holiday, check whether it moves to the next working day.

Counting days in spreadsheets

If you work with dates often, spreadsheet programs can help. Most store dates as numbers, so subtracting one date from another gives the number of days between them. Many also have functions for working days that exclude weekends and let you supply your own list of bank holidays. The key is to keep that holiday list up to date and to use the correct nation's holidays, as Scotland and Northern Ireland have different ones from England and Wales.

When you share a spreadsheet, check that everyone uses the same date format. UK dates are written day first (15/10/2026), while US dates are written month first (10/15/2026), and mixing them up is a common source of errors. Writing the month as a word, such as 15 Oct 2026, avoids confusion entirely.

Time zones and deadlines

For deadlines that involve other countries, remember that a day ends at different times around the world. A deadline of midnight on a given date in London is still the afternoon of that date in New York.