About Working Days Calculator UK
This site exists to do one thing well: calculate working days in the UK. It adds and subtracts business days, counts working days between two dates, and answers the common questions HR, payroll, legal, and project teams have about UK bank holidays — including the regional differences between England & Wales, Scotland, and Northern Ireland.
Who built this
The calculator was built by a small UK-based team led by a practising conveyancing solicitor who spent years counting working days by hand for completion dates, notice periods, and service deadlines — and got tired of US-centric tools that ignore bank holidays or treat the UK as one calendar. The day-to-day work is split between the legal and operational side (deciding what a working-day question actually means in practice) and the engineering side (making sure the answer is correct to the day). It is an independent project, not affiliated with gov.uk, ACAS, or any government body.
Why we built it
Most generalist date calculators are built for US audiences. They either ignore UK bank holidays altogether or treat the UK as a single calendar — which is wrong. Scotland has 2nd January and St Andrew’s Day. Northern Ireland adds St Patrick’s Day and the Battle of the Boyne. Easter Monday is a bank holiday in two of the three regions, not all three. Anyone tracking contracts, notice periods, court deadlines, or payroll in the UK needs a calculator that gets this right, every time, for the correct region.
Our methodology
Bank holiday dates come directly from the official gov.uk bank holiday feed, which is the authoritative source and the same data government departments rely on. That feed includes substitute days — when a holiday falls at a weekend and is observed on the following Monday or Tuesday — and we use those substitute dates, not the original, because they are the ones that count for pay and contractual purposes.
Every calculation runs in UTC so the spring and autumn clock changes can never shift a result by a day, and the working-day engine is covered by an automated test suite that has to pass before any change goes live. We count from the day after the start date by default, which matches how the great majority of UK contracts, court rules, and notice periods are written (“within X working days of” an event). Where a definition is genuinely contested, we explain the options rather than quietly picking one.
How often we review the content
We re-check the bank holiday data against gov.uk at least once a quarter, and immediately whenever the government announces a change — for example a one-off holiday for a royal or national event, which has happened several times in recent years. Guides and explanatory pages are reviewed at least annually, and sooner when the law or ACAS guidance they refer to changes. Each year, month, and bank-holiday page is generated from the same underlying dataset, so a single data update flows through to every page at once and nothing is left stale.
What we don’t do
We are not a substitute for legal, financial, or tax advice. Working- day calculations here are correct for the bank holiday calendars published by gov.uk, but a specific contract may use its own definition of “business day” or apply a different rule when a deadline falls at a weekend. Always check the document that governs your obligation, and take professional advice on anything that carries real consequences.
Get in touch
Spot a bug, want a feature, or think a date is wrong? Tell us via the contact page. Corrections to bank holiday dates are taken seriously — though, as above, they need to be reflected on gov.uk first, since that is our source of truth.