Date Calculator — Days Between Dates

This calculator finds the exact number of days, weeks, months and years between any two dates. You can choose to include or exclude weekends and UK bank holidays, which makes it useful for calculating working days for employment notice periods, project timelines or legal deadlines. Between 1 January and 31 March 2026, for instance, there are 89 calendar days, or 12 weeks and 5 days, but only 63 working days once weekends come out and 61 once bank holidays go too.

The UK has eight permanent bank holidays in England and Wales, while Scotland has nine and Northern Ireland ten. The tool accounts for these automatically based on the nation you select, and it handles leap years correctly. HMRC and Companies House count business days for many filing deadlines, and the Civil Procedure Rules take a stricter line again, since under CPR Part 2 days usually means clear days, excluding both the day of the act and the day of expiry.

You can also add or subtract a set number of days, weeks or months from a given date, which covers due dates, contract expiry and the end of a notice period. Adding days is straightforward, so 15 March plus 90 days lands on 13 June. Months are the awkward case. 31 January plus 1 month gives 28 February, or 29 in a leap year, and UK contract law generally reads one month from as the same date next month, or the last day if that date is absent. Years behave the same way, so 29 February 2024 plus a year is 28 February 2025.

The gap between working days and calendar days widens quickly. Thirty calendar days from 1 December 2026 reaches 31 December 2026, but 30 working days from the same start does not arrive until roughly 12 February 2027, depending on how the Christmas and New Year holidays fall that year. Any contract counting in days is worth checking on that basis, and legal drafting should state whether it means calendar months or 30-day blocks, because the two answers separate every time a month runs short or long.

A handful of UK deadlines come up often enough to be worth memorising. Consumer cooling-off on distance contracts runs 14 calendar days from delivery, a mortgage offer usually carries a 7-day reflection period, and an Employment Tribunal claim must be brought within 3 months less 1 day of the incident. Limitation on a simple contract is 6 years and on a deed 12 years, while personal injury claims run 3 years. HMRC can assess 4 years back as standard, 6 years where a taxpayer was careless and 20 years where the error was deliberate. Capital Gains Tax on a residential property disposal has a 60-day reporting and payment window, and the executor's year means 12 months from the grant.

Britain runs several parallel years and they do not line up. The academic year covers September to July in schools and October to June at universities, with semesters typically running 12 teaching weeks. The personal tax year and the ISA year both run 6 April to 5 April. Councils work to 1 April and 31 March for Council Tax, business rates and election cycles, and the government fiscal year uses the same dates, sitting 5 days away from the individual tax year for entirely historical reasons. Companies House sets an accounting reference date on the anniversary of the incorporation month, which is different again.

Counting between two events is simple subtraction, so 5 October 2026 back to 12 March 2024 gives 2 years, 6 months and 23 days, or 938 days in total. Anniversaries are the same date plus a number of years, and milestone counts work identically, with 100 days meaning 100 calendar days later and 1,000 days landing roughly 2 years and 9 months out. Anyone born on 29 February 2024 waits until 29 February 2028 for a genuine birthday, and most legal documents accept 28 February or 1 March in between. Write dates in ISO 8601 form, as 2026-03-15, when they cross borders, because UK order gives 15/03/2026 and the United States writes the same day as 03/15/2026.