SwiftShort answer
Business days are weekdays excluding published holidays, counted from the day after the start date. A 45-business-day term from Friday, October 16, 2026 lands on Tuesday, December 22, 2026 once Thanksgiving (Nov 26–27) and Christmas (Dec 25) are removed — 67 calendar days in total. Always confirm which holiday calendar the contract names.
Scope and assumptions
Holiday calendars differ by country, state and employer; some contracts count the start date or roll weekend/holiday deadlines to the next business day. For legal deadlines, verify the governing rule or consult counsel. This page is informational.
The deadline disputes I have seen come down to one habit: someone counted the start date. Don't. Business days are weekdays minus the holidays on your calendar, counted from the day after the start date — and the result is a deadline you can defend in writing.
Where to read next
- Plain calendar difference? → Days Between Dates guide
- Add or subtract N days? → Date From Days guide
- Hours and overtime, not days? → Hours guide
What is a work days calculator?
A work days calculator counts business days between two dates — weekdays minus holidays — and converts a term like "45 business days" into a calendar deadline. It exists because contract terms, SLAs and net-15 invoices count business days while calendars count every day.
How to count business days between dates
The rule has two halves. Forward counting starts the day after the start date (today is day zero), and every Saturday, Sunday and named holiday is skipped. Run backwards, the same span is:
Business days between = calendar days − weekend days − holidays falling inside the span
Worked example: business days excluding Thanksgiving and Christmas
A contract signed Friday, October 16, 2026 promises delivery in 45 business days. The contract names the US federal holiday calendar, which removes Thanksgiving (Nov 26–27) and Christmas (Dec 25).
Counting forward, day 1 is Monday, October 19:
| Week | Business days | Running count |
|---|---|---|
| Oct 19–23 | 5 | 5 |
| Oct 26–30 | 5 | 10 |
| Nov 2–6 | 5 | 15 |
| Nov 9–13 | 5 | 20 |
| Nov 16–20 | 5 | 25 |
| Nov 23–27 | 3 (Thanksgiving) | 28 |
| Nov 30–Dec 4 | 5 | 33 |
| Dec 7–11 | 5 | 38 |
| Dec 14–18 | 5 | 43 |
| Dec 21–25 | 2 (Christmas) | 45 |
Deadline: Tuesday, December 22, 2026 — 67 calendar days after signing.
The calendar-day equivalent is the number to quote when someone asks "why so long?" Sixty-seven days sounds excessive next to "45" until you see the three holidays and ten weekends doing the work.
Net 15 business days due date: worked example
An invoice dated Monday, November 2, 2026 with net-15 business-day terms:
Nov 3–6 = 4 · Nov 9–13 = 9 · Nov 16–20 = 14 · Nov 23 = 15
Due: Monday, November 23, 2026 — no federal holidays fall inside the window.
Had the terms said "net 15" without the word business, the reading would commonly be calendar days — November 17, 2026. One missing word, six days of difference, and a late fee riding on the interpretation. When drafting or receiving terms, make the unit explicit.
The reverse question: 10 business days from November 30, 2026
The formula runs both directions. Business days between Oct 16 and Dec 22, 2026:
67 calendar days − 20 weekend days − 2 in-span holidays (Nov 26–27) = 45 business days
Note that Christmas (Dec 25) sits outside this span and correctly does not subtract. The formula only removes holidays that fall between the two dates.
A second pattern worth recognizing — a support SLA promising a fix in 10 business days, opened Monday, November 30, 2026:
Dec 1–4 = 4 · Dec 7–11 = 9 · Dec 14 = 10 → due Monday, December 14, 2026
No holidays intervene, so the count is pure weekdays.
What to verify before relying on a count
- Which holiday calendar the agreement names — federal, state, or company-specific.
- Whether the start date counts — most contract terms begin counting the next business day.
- The weekend roll rule — many agreements move a weekend deadline to the next business day, but only if written.
- The local work week — Sunday–Thursday is standard across much of the Middle East, so an "obvious" Monday–Friday count can be wrong for a Gulf-based counterparty.
Every date on this page is a business-day count: use the Work Days Calculator and business-days tool to run any span with the holidays removed. The longer version: how many work days are left in 2026.
Four ways a business-day count goes wrong
- Counting the start date as day one.
- Forgetting a holiday that falls mid-week and bends the count.
- Treating "net 15" as automatically business days.
- Assuming every country's work week runs Monday to Friday.
FAQ
Q: How do you count business days between two dates? Start counting the day after the start date, skip Saturdays, Sundays and the holidays on your calendar, and stop at the end date.
Q: Does the start date count as a business day? Usually not for contract terms — day 1 is typically the next business day — but read the clause; some count inclusively.
Q: Which holidays count? Whichever calendar the contract or policy names; US federal contracts commonly use the 11 OPM holidays.
Q: 45 business days from October 16, 2026 is what date? Tuesday, December 22, 2026, when Thanksgiving (Nov 26–27) and Christmas (Dec 25) are excluded.
Q: What if the deadline lands on a weekend? Many contracts roll it to the next business day, but that rule must be written into the agreement — do not assume it.
Q: Do business days mean Monday to Friday everywhere? No. Much of the Middle East runs Sunday to Thursday, and some countries run Saturday to Wednesday.
Q: Are net-15 terms calendar or business days? Check the invoice; "net 15" without qualification is commonly read as calendar days, while "15 business days" is explicit.
Q: Does a holiday I don't observe still count? Only the holidays named in the agreement count, even if your office is closed for other reasons.
Sources: OPM federal holiday schedule (opm.gov); US DOL FLSA framework (dol.gov); business-day conventions (en.wikipedia.org/wiki/Business_day).
Disclaimer: Holiday calendars differ by country, state and employer; some contracts count the start date or roll weekend deadlines to the next business day. For legal deadlines, verify the governing rule or consult counsel. This page is informational.