How to use
- Days between: pick a start date and an end date. You get the number of days between them, the same span in months and days, in weeks and days, and the number of working days (Monday to Friday).
- Add or subtract: pick a start date, enter a number, choose the unit (days, working days, months or years) and whether to add or take away. You get the date and the day of the week. The quick picks fill in common amounts such as 30 days or 10 working days.
Dates are written day first, so 13/10/2026 is 13 October 2026.
How it is calculated
Days between = end date − start date. For example, 1 January 2026 to 31 December 2026 is 364 days, or 365 when both the start and end date are counted.
Working days count every Monday to Friday from the start date up to the day before the end date. Leap years are handled automatically, because the sum uses real calendar dates, 29 February included.
Examples
From Tuesday 13 October 2026:
| To | Days | In months and days | In weeks | Working days (Mon–Fri) |
|---|---|---|---|---|
| Christmas Day, Fri 25/12/2026 | 73 | 2 months, 12 days | 10 weeks, 3 days | 53 |
| Self Assessment deadline, Sun 31/01/2027 | 110 | 3 months, 18 days | 15 weeks, 5 days | 79 |
The 79 working days to 31 January include three bank holidays in England and Wales (25 and 28 December, 1 January), so the real figure there is 76.
Adding 20 working days to Tuesday 13/10/2026 gives Tuesday 10/11/2026. No bank holidays fall in that stretch in England and Wales, so it is also the real answer there.
Bank holidays in England and Wales
Take these off the working-day count yourself if they fall inside your dates:
| 2026 | 2027 |
|---|---|
| Thu 1 January – New Year’s Day | Fri 1 January – New Year’s Day |
| Fri 3 April – Good Friday | Fri 26 March – Good Friday |
| Mon 6 April – Easter Monday | Mon 29 March – Easter Monday |
| Mon 4 May – Early May bank holiday | Mon 3 May – Early May bank holiday |
| Mon 25 May – Spring bank holiday | Mon 31 May – Spring bank holiday |
| Mon 31 August – Summer bank holiday | Mon 30 August – Summer bank holiday |
| Fri 25 December – Christmas Day | Mon 27 December – Christmas Day (substitute day) |
| Mon 28 December – Boxing Day (substitute day) | Tue 28 December – Boxing Day (substitute day) |
Scotland and Northern Ireland have different bank holidays, such as 2 January and St Andrew’s Day in Scotland, and St Patrick’s Day and 12 July in Northern Ireland. GOV.UK lists them all.
Common uses
- Countdowns: days until a holiday, an exam, a wedding or Christmas.
- Work: notice periods, probation, the 30-day or 60-day payment terms on an invoice, and how many working days of leave a trip uses.
- Deadlines: the 31 January Self Assessment deadline, or anything set as “within 14 days” or “within 3 months”.
- Ages and anniversaries: for an exact age from a date of birth, use the age calculator.