Business days calculator

How the days are counted

This is not a worldwide holiday database. It is three counting rules on one page, so you can match the one your invoice or SLA actually uses.

Between dates includes both ends when they are working days — the same rule as Excel NETWORKDAYS. A Monday-to-Friday week is 5 business days. Friday to the next Friday is 6.

Add / subtract treats the start date as day 0, like Excel WORKDAY. Add 1 to a Friday and you land on Monday, unless Monday is a holiday.

Invoice / Net 30 uses calendar days, which is how most trade terms are written. Invoice dated Friday, August 28, 2026 plus 30 calendar days is Sunday, September 27, 2026. Turn on “due on business days only” and that Sunday moves to Monday, September 28. Labor Day 2026 is Monday, September 7 — it sits inside the 30 days but does not change a Sunday due date.

Weekend means Saturday and Sunday. There is no half-day, no Saturday-working schedule, and no state holiday pack in this version.

Worked example (business days, not trade Net 15)

Invoice dated Friday, August 21, 2026. Add 15 business days with federal observed holidays on. Labor Day 2026 is Monday, September 7. The due date is Monday, September 14, 2026. With holidays off, it would be Friday, September 11. Trade Net 15 is still calendar days — use Invoice / Net 30 for that.

Federal observed holidays used here

Copied from the OPM year tabs for 2025–2027. Inauguration Day 2025 is the same date as MLK Day and is DC-area only, so it does not add a second nationwide off-day.

FAQ

How many working days are between two dates?

Both the start date and the end date count if they are weekdays and not in the holiday set. That is the same rule as Excel NETWORKDAYS. Saturday and Sunday are weekends. A Monday-to-Friday week is 5 business days; Friday to the next Friday is 6.

When is a Net 30 invoice due?

Net 30 is 30 calendar days after the invoice date. The invoice date is day 0, so you add 30. An invoice dated Friday, August 28, 2026 is due Sunday, September 27, 2026 on the calendar. If payment is only accepted on a business day, turn on “due on business days only” and it moves to Monday, September 28. Labor Day 2026 is Monday, September 7 — it sits inside the 30 days but does not move that Sunday due date.

Is Net 30 calendar days or business days?

Most trade terms — Net 15, Net 30, Net 45, Net 60 — mean calendar days. Use Invoice / Net 30 for that. Add / subtract is different: it uses Excel WORKDAY (business days only), which is useful for SLAs, not for reading an invoice. Read your contract.

What if a Net 30 due date falls on a weekend or holiday?

Invoice mode still prints the calendar due date. Check “due on business days only” to roll a Saturday, Sunday, or US federal observed holiday forward to the next weekday that is not in the holiday set. The term itself does not skip weekends while counting — only the landing day can move.

Which holidays does this skip?

Optional US federal observed dates for 2025, 2026, and 2027, copied from the OPM federal holiday schedule (5 U.S.C. 6103), including in-lieu Fridays and Mondays when a holiday falls on a weekend. That is not a guarantee a bank, court, or counterparty is closed. Add a custom date if your buyer observes something else. In invoice mode these dates only move the due date when “due on business days only” is on.

How do I add N business days to a date?

Switch to Add / subtract. The start date is day 0, like Excel WORKDAY. Add 1 to a Friday and you land on Monday, unless Monday is a holiday. Negative numbers go backward. The “Net 30 business days” preset is this mode — it is not trade Net 30.

Does Net 30 start the day you send the invoice or the day after?

This page treats the invoice date as day 0, then adds 30 calendar days. An invoice dated Friday, August 28, 2026 is due Sunday, September 27, 2026 on the calendar (not Saturday the 26th). Some contracts say “30 days after receipt” instead of invoice date — that is not what this calculator does. Read the contract. Markup vs margin prices the line; break-even counts units until fixed is covered; this page only lands the due date.

Does Net 30 change my break-even unit count?

No. Break-even units = fixed costs / (price − variable cost) is how many jobs cover fixed on paper — $2,000 / $20 = 100 units. Net 30 is when cash is due after you invoice: invoice date is day 0, then add 30 calendar days. You can hit 100 units and still wait until the Net 30 due date for payment. Use break-even for the unit count; use this page for the due date. Neither is a bank balance.

Are OPM federal holidays the same as US bank or Fed ACH holidays?

No. This page’s holiday toggle is the OPM federal observed schedule (5 U.S.C. 6103) for federal employees — not the Federal Reserve bank holiday calendar that gates Fedwire and ACH settlement. The lists overlap most years, but they are not the same job: Good Friday can close markets while OPM stays open; Inauguration Day is DC-area on the OPM tab and is not a nationwide Fed holiday. A Net 30 due date that lands on a Fed holiday may not settle until the next banking day even if you rolled with the OPM toggle. Confirm with your bank or processor; add a custom chip if your buyer’s calendar differs.

Is Net 30 EOM the same as Net 30?

No. Plain Net 30 is invoice date as day 0, then +30 calendar days. Net 30 EOM (end of month) usually means: go to the last day of the invoice month, then add 30 calendar days. Fixture: invoice dated Friday, August 15, 2025 — plain Net 30 lands Sunday, September 14, 2025; Net 30 EOM lands Tuesday, September 30, 2025 (Aug 31 + 30). This page’s Invoice / Net 30 mode is plain Net 30 only — it does not shift to month-end first. Read the contract for EOM / Net 10 EOM / 2/10 Net 30 wording. Markup vs margin prices the line; this page only lands due dates. Calendar math, not legal advice.

Does adding 30 business days give the same due date as Net 30?

No. Trade Net 30 is 30 calendar days from the invoice date (invoice = day 0). Add / subtract with N=30 is Excel WORKDAY — it skips Saturdays, Sundays, and (when the holiday toggle is on) OPM federal observed holidays, so it lands later. Fixture: invoice Friday, August 28, 2026. Invoice / Net 30 calendar lands Sunday, September 27, 2026; with “due on business days only” → Monday, September 28, 2026. Add / subtract +30 business days with federal observed holidays on (Labor Day 2026 = Mon Sep 7 skipped) lands Monday, October 5, 2026. So Net 30 ≠ “30 business days.” Use Invoice / Net 30 for trade terms; use Add / subtract for SLA-style business-day deadlines. Cash timing / pricing siblings: break-even and markup vs margin.

Does Black Friday (the day after Thanksgiving) count as a holiday on this page?

No. The optional OPM federal observed holiday toggle follows 5 U.S.C. 6103. Thanksgiving Day is on that list; the Friday after (Black Friday / day after Thanksgiving) is not a federal holiday, so with the toggle on it still counts as a business day. Many private offices close that Friday — add it with a custom holiday chip if your counterparty does. Fixture: Thanksgiving 2025 is Thursday, November 27; Black Friday Friday, November 28 still counts. Wednesday, November 26, 2025 + 2 business days with federal observed on → Friday, November 28 (not Monday, December 1). Invoice / cash siblings: markup vs margin and break-even.

Does Good Friday count as a holiday on this page?

No. With the OPM federal observed holiday toggle on, this page follows 5 U.S.C. § 6103 / OPM observed federal holidays. Good Friday is not on that list, so it still counts as a business day here — even though many banks and some private offices close. If your office treats Good Friday as closed, add it as a custom holiday chip. Fixture: Good Friday 2026 is Friday, April 3; Wednesday, April 1, 2026 + 2 business days with federal observed on → Friday, April 3 (not Monday, April 6). Contrast: Thanksgiving is skipped when the toggle is on. Invoice / cash siblings: markup vs margin and break-even.

If the invoice is dated on a Saturday, is that Saturday still day 0 for Net 30?

Yes. Plain calendar Net 30 treats the invoice date as day 0 even when it falls on a weekend — you do not slide day 0 to the next Monday. Fixture: invoice dated Saturday, August 29, 2026 → +30 calendar days → Monday, September 28, 2026. Trap: moving day 0 to Monday, August 31 and adding 30 lands Wednesday, September 30 — wrong for plain Net 30. The optional business-day roll only moves the landing day when the due date hits a weekend/holiday; it does not change which calendar day is day 0. Invoice / cash siblings: markup vs margin and break-even.

My office stays open on Columbus Day and Veterans Day. Does this page still skip them?

Yes, while the OPM federal observed toggle is on. Columbus Day (Monday, October 12, 2026) and Veterans Day (Wednesday, November 11, 2026) are both on the 5 U.S.C. § 6103 list, so this page skips them like Thanksgiving — even though many private employers stay open both days. Fixture: Monday, November 9 to Friday, November 13, 2026 counts 4 business days with the toggle on, 5 with it off. Tuesday, November 10 + 1 business day → Thursday, November 12 with the toggle on, Wednesday, November 11 with it off. Fix: if your shop works those days, turn the federal toggle off and add custom chips only for the days you actually close (for example Thanksgiving and Christmas). Invoice / cash siblings: markup vs margin and break-even; payroll week: time card calculator.

Is this legal advice?

No. This is calendar math, not legal, payroll, SLA, or collections advice. Holidays are US federal observed dates from OPM, not a filing deadline and not a promise that any office is closed. Confirm terms with your counterparty.