Business Days Calculator

What is a business days calculator?

A business days calculator finds the number of working days between two dates, or works out what date you land on after adding or subtracting a number of working days from a start date. Business days means days that aren't weekends and aren't holidays — Monday through Friday in most places, minus whatever days off your organization actually observes.

This tool has two modes. Count mode takes a start date and an end date and returns how many business days sit between them, with a toggle for whether the end date itself should be included. Add/subtract mode takes a single date, a number of business days, and a direction — after or before — and returns the resulting calendar date along with the weekday it falls on.

Under the hood, dates are normalized to UTC before any counting happens, so a daylight-saving clock change — which makes a real day 23 or 25 hours long somewhere — can never shift the count by one. Counting itself is done as whole weeks plus a remainder of at most six days, not by stepping through every date one at a time, so a range spanning forty years costs no more to compute than a range spanning one week.

How to use it

1. Pick a mode: choose Count to find the number of business days between two dates, or Add/Subtract to find the date a set number of business days before or after a single date.
2. Set the working week and any holidays, toggling individual weekdays or using a preset such as Saturday and Sunday, Friday and Saturday, or Sunday only, then pasting any dates to exclude, one per line in YYYY-MM-DD format.
3. Read the result, which appears immediately with a breakdown of total calendar days, weekend days excluded, holidays excluded, and any pasted holidays that were ignored because they already fell on a weekend — then copy it with one click.

Why there is no country holiday list

This calculator deliberately has no dropdown of national public holidays to pick from. That's a decision worth explaining rather than hiding, because it's the opposite of what most similar tools do.

We tested the most widely used holiday dataset on npm against the UK government's own machine-readable bank holiday feed at gov.uk/bank-holidays.json, across all three UK jurisdictions — England and Wales, Scotland, and Northern Ireland — and all ten years the feed covers, 2019 to 2028. There were 43 disagreements between the two.

42 of those 43 were harmless: holidays landing on a Saturday or Sunday, where the government feed lists only the substitute weekday taken instead. For a business-day calculator that changes nothing, because the original day is already excluded as a weekend regardless of which one the dataset names.

The one that mattered: the dataset does not have Monday 15 June 2026, Scotland's World Cup bank holiday. That holiday was created by Royal Proclamation approved by the King in February 2026, roughly four months before it happened. It falls on an ordinary working Monday, so leaving it out genuinely changes the answer.

Size wasn't the reason we left it out. The dataset in question is about 236 KB gzipped, comfortably under the roughly 432 KB gzipped budget this site already accepts elsewhere for a PDF library. The real reasons are that the data is derived from Wikipedia, is licensed CC BY-SA 3.0, and — as measured here — goes stale exactly when a government invents a holiday at short notice, which is precisely the moment someone computing a real deadline would be relying on it.

There's a further nuance, from the Scottish government's own coverage of the day: even that officially proclaimed holiday wasn't universal. Whether an individual actually got the day off depended on their employer or local council. A single national answer would have been wrong for a lot of people anyway.

So the visitor's own list is treated as the authority here, not a bundled dataset. An office calendar knows things no public dataset does: company shutdown days, regional observances, the half-day nobody ever wrote down anywhere official.

Where business days matter more than calendar days

Invoice payment terms are usually written in business days, not calendar days — “net 30 business days” from an invoice date lands on a different, later date than 30 calendar days, and Add/Subtract mode gives you that exact date to put in the reminder.

Legal and administrative filing deadlines are frequently defined in business days too, and getting the count off by even one can matter. Count mode with the end date included or excluded, set to match how the deadline is actually worded, gives a precise answer rather than a mental estimate.

Shipping estimates quoted as “3 to 5 business days” are really a range of calendar dates once weekends and any known holidays are factored in — useful to check against today's date before promising a delivery window to a customer.

Notice periods in employment contracts and tenancy agreements are another common case: a fixed number of business days from a resignation or termination date, which Add/Subtract mode turns into a concrete calendar date and weekday.

The weekend selector exists because the working week genuinely differs by region. Most of Europe and the Americas work Monday to Friday with Saturday and Sunday off, but much of the Middle East and North Africa treats Friday and Saturday as the weekend instead, and some countries observe only Sunday as a day off. Switching the preset changes which days count as business days without touching anything else.

Why is it free?

Every calculation here runs in your browser. Your dates and any holidays you paste in never leave your device, there's no account to create, and nothing is watermarked. That's true of every tool on this site — it's a deliberate choice about what's worth building, not a limited trial of something bigger.