45 business days from today in the UK

At nine weeks the holiday calendar starts to dominate

Short counts are decided by weekends. A window of forty-five working days contains sixteen to twenty weekend days wherever it starts, eighteen when it runs exactly nine weeks, so weekends are close to a constant and stop being interesting. What varies is how many bank holidays the window happens to cover, and over nine weeks that number ranges from none to several.

The practical consequence is that two forty-five-day windows agreed in the same contract, one starting in January and one starting in March, do not have the same amount of working time in them measured against the calendar. They have the same number of working days by construction, which is the point of counting that way, but the calendar dates land further apart than most people expect.

Forty-five working days against real dates

The calendar span below is always the larger figure: sixteen to twenty weekend days sit on top of the forty-five working ones, plus a day for every bank holiday that falls on a weekday inside the window.

Closures across these nine working weeks

No England and Wales bank holiday falls between the reference date and the answer, so every day taken out of this count is a Saturday or a Sunday.

Drafting a forty-five-working-day clause

• Say which bank holiday list governs. Over nine weeks the difference between the England and Wales list and a UK-wide one is real.
• Say what happens to a holiday newly appointed by proclamation. Section 1(3) of the 1971 Act allows one to be created at short notice, and long windows outlive the calendar they were drafted against.
• Say whether the count starts on the trigger day or the next working day, because at this length nobody will remember what was intended.

Where this page's law and dates come from

Each link below was opened on September 7, 2026 and checked against the wording quoted above it. Where a period on this page is trade practice rather than legislation, the text says so in those words instead of reaching for a citation.