Counting business days sounds straightforward until you realize holidays differ by country, some months have irregular weekends, and deadlines that land on weekends shift to Monday. Here’s how it actually works.
What Counts as a Business Day?
A business day is any day that is:
- Not a Saturday or Sunday
- Not a public holiday in the relevant jurisdiction
In most countries, this means Monday through Friday minus national holidays. The exact holidays vary — the US observes 10–12 federal holidays per year, the UK has 8 bank holidays in England and Wales (more in Scotland), and Germany has up to 19 depending on the state.
The Basic Method: Counting Manually
For short spans (a week or two), manual counting works fine:
- Start at your start date (do not count it)
- Move forward one day at a time
- Skip Saturdays and Sundays
- Skip any public holidays in the period
- Stop when you’ve counted the required number of business days
Example: What is 5 business days after Monday, April 14?
| Day | Date | Count? |
|---|---|---|
| Mon | Apr 14 | Start (don’t count) |
| Tue | Apr 15 | 1 |
| Wed | Apr 16 | 2 |
| Thu | Apr 17 | 3 |
| Fri | Apr 18 | 4 |
| Sat | Apr 19 | Skip |
| Sun | Apr 20 | Skip |
| Mon | Apr 21 | 5 ✓ |
Answer: Monday, April 21.
The Formula for Business Days Between Two Dates
For calculating the number of business days between two dates (without accounting for holidays):
Business days = Total days − Weekend days
Weekend days in a range can be calculated as:
Weekend days = 2 × ⌊(Total days) ÷ 7⌋ + adjustment for partial week
In practice, this is easier to calculate with a tool — the formula handles the partial-week correction automatically. Use our business days calculator to get the exact count without doing this math by hand.
Why Deadlines That Fall on Weekends Shift
Most legal, financial, and contractual deadlines follow this rule:
If the deadline falls on a weekend or holiday, it moves to the next business day.
This is standard in contract law, court filings, and financial settlement:
- A payment due Saturday is due Monday
- A filing due on Christmas (if a weekday holiday) is due the next business day
Some contracts specify “calendar days” instead of business days — in that case, no shifting applies and weekends count. Always check which definition your contract or regulation uses.
Holiday Differences by Country
This is where business day calculations get complicated. If you’re working with international counterparts, their holidays will differ from yours.
United States (Federal Holidays)
The US has 10 federal holidays plus occasional one-time observances. Banks and most corporate offices follow this schedule:
- New Year’s Day (Jan 1)
- Martin Luther King Jr. Day (3rd Monday of January)
- Presidents’ Day (3rd Monday of February)
- Memorial Day (Last Monday of May)
- Juneteenth (June 19)
- Independence Day (July 4)
- Labor Day (1st Monday of September)
- Columbus Day (2nd Monday of October)
- Veterans Day (Nov 11)
- Thanksgiving (4th Thursday of November)
- Christmas Day (December 25)
United Kingdom
England and Wales observe 8 bank holidays; Scotland and Northern Ireland have different sets. Key dates:
- New Year’s Day, Good Friday, Easter Monday
- Early May Bank Holiday, Spring Bank Holiday
- Summer Bank Holiday (different date in Scotland)
- Christmas Day, Boxing Day (Dec 26)
Germany
Germany has 9 national holidays, but states add their own — Bavaria observes up to 13, while Berlin has 10. This matters if you’re calculating a deadline that crosses November 1 (All Saints’ Day, Bavaria only) or Epiphany (January 6, Bavaria/Baden-Württemberg/Saxony-Anhalt only).
Practical Advice
For international deadlines, use the holidays of the governing jurisdiction — the country whose law applies to the contract or transaction. When in doubt, add a buffer day.
Common Business Day Calculation Scenarios
”Net 30” Payment Terms
Net 30 means 30 calendar days from the invoice date, not 30 business days. Net 30 on an invoice dated April 1 = due May 1, regardless of weekends. If May 1 is a Sunday, most practices treat May 2 (Monday) as the effective due date, though contracts vary.
Net 30 business days would be significantly longer — approximately 6 calendar weeks.
Contract Deadlines
Legal contracts typically specify “business days” for notice periods. A 5-business-day notice given on Thursday afternoon (after business hours) may not start until Friday morning — or even Monday, depending on jurisdiction and whether “given” means sent or received.
Court Filings
Court rules often exclude the start date and include the end date, and may have their own definition of which holidays count. Always verify the specific court’s local rules.
Construction and Project Management
Construction contracts use “working days” — same as business days but may also exclude weather days or other project-specific exclusions. Check the contract definition.
How to Add Business Days to a Date (Quick Method)
- Count full weeks: divide by 5, multiply by 7 to get calendar days
- Handle the remainder: add the leftover days, skipping weekends
- Subtract any holidays in the span
Example: 15 business days from March 3 (Monday)
- 15 ÷ 5 = 3 full weeks = 21 calendar days → March 24
- 15 ÷ 5 has no remainder, so March 24 is the raw answer
- Check March 3–24 for holidays in your jurisdiction
- If no holidays, March 24 is the answer
For any span with holidays, or spans not divisible by 5, use the business days calculator — it handles the edge cases automatically.
Summary
Business days are weekdays minus public holidays. For deadline calculations: if the deadline lands on a weekend or holiday, it shifts to the next business day. Holiday sets vary by country and even by region within a country. For anything involving a contract, court filing, or international transaction, verify which jurisdiction’s holidays apply.
Use the business days calculator to count exactly how many business days fall between any two dates, or to find what date falls N business days from now.