The business days calculator adds or subtracts working days (Monday through Friday) from any start date, skipping weekends automatically. Enter a start date and a number of business days — use a negative number to go backwards. Public holidays are not excluded in the current version, as these vary by country and employer.
The formula
result = start_date + N business days
(advance 1 calendar day at a time, count only Mon–Fri)
The algorithm steps one calendar day at a time in the chosen direction, counting only days where day_of_week ∉ {Saturday, Sunday} until N working days have been counted.
Practical examples
Example 1 — Standard 5-day lead time
Order placed on Wednesday, May 28, 2026. Delivery promised in 5 business days.
Thu May 28 (day 0) → Thu Jun 4 (day 5, skipping weekend)
Result: Thursday, June 4, 2026
Example 2 — Counting backward for a deadline
A document is due Friday, June 6, 2026. You need 10 business days to prepare it.
Jun 6 − 10 business days → skips two weekends → Result: Monday, May 25, 2026
Start work no later than May 25.
Example 3 — Large number of business days
Contract requires 90 business days from signing on January 2, 2026.
90 business days ÷ 5 per week ≈ 18 calendar weeks + weekends = approximately May 8, 2026.
Result: May 8, 2026 (exact, accounting for actual weekends).
Common mistakes
Starting the count on day 1 instead of day 0. "5 business days from Monday" means Monday is day 0 and Friday is day 5 — the result is Friday, not the following Monday. The calculator uses day 0 as the standard.
Forgetting public holidays. This tool counts Mon–Fri only. If your jurisdiction observes a public holiday within the window, subtract it manually from the result.
Using calendar days instead of business days for legal notices. Many legal and financial deadlines specify business days. "30 calendar days" and "30 business days" differ by approximately 8–9 days (two weekends per week × 4–5 weeks).
International and regional variations
| Country | Standard working days | Notes |
|---|---|---|
| United States | Mon–Fri | Federal holidays vary; this tool does not exclude them |
| United Kingdom | Mon–Fri | Bank holidays differ by England, Scotland, Wales, N. Ireland |
| Middle East (some countries) | Sun–Thu | Weekend is Fri–Sat in some Gulf states |
| Israel | Sun–Thu | Friday–Saturday is the weekend |
| Most of Europe | Mon–Fri | Public holidays vary by country; not excluded here |
Quick reference — business days per period
| Period | Approximate business days |
|---|---|
| 1 week | 5 |
| 2 weeks | 10 |
| 1 month | ≈ 21–23 |
| 1 quarter | ≈ 63–66 |
| 1 year | ≈ 260–262 |