Quick answer
Business days are the Monday to Friday dates from the start to the end date, inclusive. January 2024 has 31 calendar days, 23 business days and 8 weekend days.
Enter a start and end date. The calculator returns business days, weekend days and calendar days.
Related tools: Days Until Calculator: Days remaining until any date (generalizes “days until June 15”, “days until Christmas” and similar pages). Days Between Dates Calculator: Number of days, weeks and months between two dates. Date Calculator: Add or subtract days, weeks, months or years from a date.
How to use the Business Days Calculator
- Pick start date.
- Pick end date.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Start date | A calendar date | — |
| End date | A calendar date | — |
Formula and method
Formula
working days = number of Monday–Friday dates from start to end, inclusive
Exact integer day arithmetic in UTC; no daylight-saving or time-zone effects.
Counts weekdays only; public holidays vary by country and are not removed.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Start date = 2024-01-01; End date = 2024-01-31.
| Result | Value |
|---|---|
| Business days | 23 |
| Weekend days | 8 |
| Calendar days | 31 |
Example 2
Inputs: Start date = 2024-01-06; End date = 2024-01-07.
| Result | Value |
|---|---|
| Business days | 0 |
| Weekend days | 2 |
| Calendar days | 2 |
Example 3
Inputs: Start date = 2024-01-05; End date = 2024-01-01.
| Result | Value |
|---|---|
| Business days | 5 |
| Weekend days | 0 |
| Calendar days | 5 |
The first line is the headline result (business days). Below it the business Days Calculator lists weekend days and calendar days, which describe the same case from other angles. Exact integer day arithmetic in UTC; no daylight-saving or time-zone effects.
Counting rules
Both dates are included, and the order of dates does not matter. January 2024 started on a Monday, with four full weeks (20 weekdays) plus Monday 29 to Wednesday 31 (3 weekdays), giving 23.
Holidays are not removed
Public holidays vary by country and employer, so the calculator counts weekdays only. Subtract holidays that fall on weekdays yourself: New Year's Day and MLK Day would reduce January 2024 to 21 working days in the US.
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Start date: entering "x" shows "Start date must be a valid date." beside that field and no result.
Choosing between the Business Days Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Days Until Calculator](/date-calendar/days-until-calculator/) | target date | Days until |
| [Days Between Dates Calculator](/date-calendar/days-between-dates-calculator/) | start date, end date and count end date? | Days between |
| [Date Calculator](/date-calendar/date-calculator/) | start date and operation | Resulting date |
| [Weeks Between Dates Calculator](/date-calendar/weeks-between-dates-calculator/) | start date and end date | Weeks and days |
| [Years Between Dates Calculator](/date-calendar/years-between-dates/) | start date and end date | Years, months and days |
Background: dates and times
Date and time results depend on the conventions a tool uses: whether the end date counts, whether weekends and holidays are skipped, how months of different lengths are handled and whether time zones are applied. This page states its convention, and the worked examples show it.
Dates use the Gregorian calendar and calendar days unless the page says otherwise; check deadlines against the rule in your contract or regulation.
Assumptions and limitations
- Inclusive of both dates
- Order of dates does not matter
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for start date to confirm this.
Frequently asked questions
Does it count weekends?
Only to report them.
How many business days in a year?
About 260 before holidays.
Can I add business days to a date?
Use a date calculator for adding days.
What does the Business Days Calculator calculate?
Count Monday–Friday working days between two dates (holidays are not excluded). It returns Business days, Weekend days and Calendar days.
What formula does the Business Days Calculator use?
working days = number of Monday–Friday dates from start to end, inclusive. Counts weekdays only; public holidays vary by country and are not removed.
What do I need to enter in the business Days Calculator?
You enter Start date and End date.
How is the result rounded or limited?
Exact integer day arithmetic in UTC; no daylight-saving or time-zone effects. Inclusive of both dates.
What are the limits of this calculator?
Inclusive of both dates. Order of dates does not matter.
What is an example of a business Days result?
With start date 2024-01-01 and end date 2024-01-31, the business days is 23.
Related calculators
- Days Until Calculator — Days remaining until any date (generalizes “days until June 15”, “days until Christmas” and similar pages).
- Days Between Dates Calculator — Number of days, weeks and months between two dates.
- Date Calculator — Add or subtract days, weeks, months or years from a date.
- Weeks Between Dates Calculator — Time between two dates in weeks.
- Years Between Dates Calculator — Time between two dates in years.
- Months Between Dates Calculator — Time between two dates in months.
Sources
- ISO 8601-1: Date and time, representations for information interchange (calendar dates, ordinal dates and week dates)
- Gregorian calendar reform, papal bull Inter gravissimas (1582): the leap-year rule used for all dates
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.