Monday through Friday, both included
- Dates:
- 2026-09-14 → 2026-09-18
- Business days:
- 5
- Weekend / holiday excluded:
- 0 / 0
Time · Workday Planning
Business Days Calculator
Count business days between two dates, or add and subtract business days while skipping weekends and optional custom holidays.
Business days are Monday through Friday in V1. Add your own holiday dates when they should be excluded.
Business Day Details
Enter one YYYY-MM-DD date per line. Commas and semicolons also work. Duplicate dates are automatically deduplicated.
Business-day planning disclaimer: This calculator uses a Monday-to-Friday workweek and only the custom holiday dates you provide. It does not automatically apply federal, provincial, state, local, banking, exchange, court, employer, or contract-specific holiday calendars. Confirm the applicable calendar when a legal, financial, filing, payment, or contractual deadline matters.
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⚡ Quick Answer
A business day in this calculator is any Monday through Friday that is not listed as a custom holiday. Count mode can include or exclude either endpoint, while Add and Subtract modes skip weekends and custom holidays automatically.
🧮 How It Works
Count mode looks at the dates inside the selected range and counts Monday through Friday after removing any custom weekday holidays. You control whether the start and end dates themselves are included.
Add and Subtract modes move one calendar day at a time conceptually, but the calculator uses deterministic civil-date arithmetic rather than local-time midnight calculations. This avoids daylight-saving-time and timezone shifts changing a date result.
📐 Business-Day Rules
| Rule | V1 behavior |
|---|---|
| Standard business day | Monday–Friday, excluding custom holidays |
| Weekend | Saturday and Sunday are excluded |
| Holiday on a weekend | Counted only as a weekend, not double-excluded |
| Duplicate holiday date | Deduplicated automatically |
| Add/Subtract zero | Returns the original start date without adjustment |
| Observed holidays | Not generated automatically; enter the applicable date manually |
🔢 Count Mode: Endpoint Rules
The start date and end date can each be included or excluded. If both dates are the same, the date can count only once. If neither endpoint is included, the same-date result is zero.
Reverse ranges are supported. When the start date is later than the end date, the business-day result is negative, while elapsed calendar days and excluded-day statistics remain non-negative.
🧪 Worked Examples
Weekday holiday excluded
- Dates:
- 2026-11-23 → 2026-11-27
- Business days:
- 4
- Weekend / holiday excluded:
- 0 / 1
Add 5 business days
- Start:
- 2026-09-14
- Business days:
- 5
- Result date:
- 2026-09-21
Subtract across a holiday
- Start:
- 2026-12-28
- Business days:
- 3
- Result date:
- 2026-12-22
🌎 Holidays and Local Calendars
Holiday calendars vary by country, province, state, employer, financial institution, exchange, court, and contract. This V1 calculator therefore does not silently assume a U.S. or Canadian statutory-holiday calendar.
If a holiday or observed holiday should not count as a business day, enter that exact date in the custom holiday field. This keeps the calculation transparent and lets you match the schedule that actually applies to your situation.
🎯 When to Use This Calculator
- • Estimating working days between project dates.
- • Planning a due date after a number of business days.
- • Counting workdays while excluding company-specific holidays.
- • Checking reverse date ranges without manually flipping the dates.
- • Comparing elapsed calendar time with actual business-day time.
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Frequently Asked Questions
What counts as a business day?
In this calculator, a business day is Monday through Friday, excluding any custom holiday dates you add. Saturday and Sunday are always treated as weekends in V1.
Can I include the start date and end date?
Yes. In Count mode, you can independently include or exclude the start date and end date. If both dates are the same, that day can count at most once.
What happens if the start date is after the end date?
The calculator supports reverse ranges. It returns a negative business-day count while calendar days, weekends excluded, and holidays excluded remain non-negative statistics.
How do custom holidays work?
Add any dates you want excluded from business-day calculations. Duplicate holiday dates are automatically deduplicated, and a holiday that falls on Saturday or Sunday is not counted twice.
How does adding business days work?
The start date itself does not consume a business day. The calculator moves forward until it reaches the requested number of Monday-to-Friday days that are not custom holidays.
How does subtracting business days work?
Subtract mode works in the opposite direction. It moves backward from the start date, skipping Saturdays, Sundays, and any custom holiday dates.
What happens if I add or subtract 0 business days?
The result remains the original start date, even if that date is a weekend or a custom holiday. No automatic adjustment is made when the requested move is zero.
Does this calculator automatically include U.S. or Canadian holidays?
No. V1 intentionally does not maintain an official holiday database or observed-holiday rules. Add the holiday dates that apply to your workplace, contract, jurisdiction, or schedule.