What counts as a business day
A business day is any day that is not a Saturday, Sunday, or public holiday. This tool counts Monday–Friday by default and optionally subtracts holidays from a chosen calendar (US Federal, UK Bank, EU Common, or your own custom list). Both endpoints are inclusive — if the start and end are the same weekday, that’s 1 business day. This inclusive counting is what trips people up on deadlines, so it’s worth confirming against your specific use case.
Three operations, one tool
| Mode | Answers |
|---|---|
| Count between dates | ”How many working days from A to B?” |
| Add business days | ”What date is 10 working days from now?” |
| Subtract business days | ”When must I start to finish by a deadline?” |
The add/subtract modes are the ones that save real time — for SLA deadlines, payment due dates, and legal notice periods, you need the calendar date that lands N working days away, skipping weekends and holidays automatically.
Where business-day math actually matters
This isn’t academic — entire business processes run on working-day counts:
- SLAs — “resolved within 5 business days” excludes the weekend the ticket sat over.
- Net terms — “Net 10 business days” payment windows.
- Settlement — US, Canadian and Mexican equities settle T+1 since May 2024; the UK and EU are still T+2 until their own move later this decade. A cross-border desk is running two different working-day clocks on the same trade.
- Legal notice — many jurisdictions count notice periods in working days.
Getting weekends and holidays right is the difference between hitting and missing a contractual deadline.
”3 business days from today” is a different question, and it’s the harder one
Counting the days between two known dates is arithmetic. The question people actually arrive with is the inverse: a courier said three business days — what date is that? That has no closed-form answer, because you cannot divide by seven and add. You have to walk the calendar forward one day at a time, skipping Saturdays and Sundays, skipping holidays, and — this is the part that catches people — skipping the holidays you land on while skipping, which can push the answer further than expected.
Three business days from a Thursday is the following Tuesday. Three business days from the Thursday before a Monday holiday is the following Wednesday. The gap between the naive answer and the right one is a day, and a day is the difference between a filing being on time or late.
The add and subtract modes here walk that calendar for you, in both directions. Subtracting is what you want for the planning version of the question: given a deadline, the last date you can start.
The holiday rule that silently shifts your answer
Picking a holiday calendar is not just ticking days off a list, because holidays move.
US federal holidays observe a weekend-shift rule. There are eleven of them since Juneteenth was added in 2021, and when one falls on a Saturday it is observed the preceding Friday; when it falls on a Sunday it is observed the following Monday. So a holiday on a weekend still consumes a working day — just not the day the calendar names. A tool that only subtracts the literal date will be off by one for those years.
UK bank holidays are not uniform across the UK. England and Wales have eight, Scotland has nine, and Northern Ireland has ten. “UK bank holiday” is not a single answer, and if your contract names a jurisdiction, that is the list you need.
The custom calendar exists for the cases neither preset covers: company shutdown weeks, regional holidays, and the surprisingly common situation of a counterparty operating on a different national calendar to yours. Use “View holidays included” to see exactly which dates were subtracted rather than trusting the count.
Holidays only count on weekdays
A subtle correctness point: the tool only deducts a holiday if it falls Monday–Friday within your range. A holiday on a Saturday is already excluded (it’s a weekend), so it doesn’t double-reduce the count. Click “view holidays included” to see exactly which dates were subtracted. For plain calendar-day spans (weekends included), use the Date Difference Calculator instead.
Calendar difference
The Calendar Difference tab above, or jump straight to it. It counts every day between the two dates — no weekends or holidays skipped.
Two ways to express a span
The same gap between two dates has two legitimate representations, and they answer different questions:
| Representation | Example | Best for |
|---|---|---|
| Calendar breakdown | 2 years, 3 months, 14 days | Ages, anniversaries, human counting |
| Total units | 805 days / 19,320 hours | Project duration, deadlines, arithmetic |
The breakdown is intuitive but depends on month lengths (see FAQ); the total is exact but ignores calendar structure. This tool shows both so you can pick the right one for the job.
Calendar-accurate, leap years included
The breakdown counts forward the way you’d count on a paper calendar: full years first, then remaining full months, then leftover days — correctly handling 28-to-31-day months and leap years. A span that crosses February 29 includes that day in the total. This matches how age and tenure are conventionally and legally counted, rather than a crude days ÷ 365.
ISO 8601 under the hood
Date inputs use the unambiguous ISO 8601 format (YYYY-MM-DD) internally, which sidesteps the locale nightmare where 01/02/03 could mean three different dates. The picker shows your local display format, but the stored value is always ISO — so there’s no ambiguity about which number is the month.
Calendar days vs working days
One important limitation: this calculates calendar days, weekends included. If you need business days — for an SLA, a payment term, or a delivery estimate — weekends and public holidays must be excluded, and holidays vary by country and year. For that, use the Business Days Calculator, which handles weekday-only counting and holiday calendars.