Business Day Calculator
Result
20
days · business days in range
Fri, July 24, 2026 → Sun, August 23, 2026
31
Dates evaluated
10
Non-working weekdays
1
Public holidays
0
Custom closures
Official holiday data 2004–2028 · refreshed Jul 22, 2026
Years covered by the snapshot use Korean Astronomy and Space Science Institute special-day data first; uncovered years use rule-based public-holiday calculations. Add holidays announced after the refresh and organization-specific closures manually, and verify critical deadlines with the relevant organization.
South Korean Holiday Basis and Automatic Coverage
Reference date and last reviewed: July 22, 2026
Calculation Basis
The calculator first uses an official public-holiday snapshot saved at build time from the Korea Astronomy and Space Science Institute special-day API and cross-checks it against national-day records marked as holidays. Years not provided by the API fall back to fixed, lunar, and substitute-holiday rules derived from the Regulation on Holidays of Government Offices. No external API is called while a visitor calculates dates.
Reference Limits
Temporary holidays or election dates announced after the latest snapshot refresh may be absent until the next data update. Organization-specific closures, local schedules, and cutoff times still require direct confirmation, and rule-based fallback for unsupported historical years can differ from the rules in force at that time.
When to Confirm Officially
For contractual deadlines, statutory filings, financial settlement dates, and administrative due dates that can create a penalty, verify the result against the relevant organization's official calendar and guidance.
Usage Tips
Match inclusion and closure rules before setting a deadline
The calculator prioritizes a build-time KASI official-holiday snapshot for contract submissions, delivery estimates, and administrative deadlines. Confirm whether the start date counts, then add company closures or holidays announced after the latest refresh.
What is Business Day Calculator?
The Business Day Calculator counts working dates in a range or finds a date N business days away after excluding non-working weekdays, South Korean public holidays, substitute holidays, and custom closures. Supported years use a build-time snapshot of official KASI holiday data first, while unavailable years fall back to statutory holiday rules.
How to Use
- 1Choose the date-range mode or the add/subtract business days mode.
- 2Enter start and end dates, or enter a base date, number of business days, and direction.
- 3Select the weekdays on which the organization normally operates and choose whether to exclude South Korean public holidays.
- 4Add company closures or holidays announced after the latest official-data refresh as custom closure dates.
- 5Review the business-day count and exclusions, or the calculated date and elapsed calendar days.
Separate boundary inclusion from holiday exclusions
Last reviewed: July 22, 2026Business days in a range
business days = dates in scope − non-working weekdays − public holidays − custom closures
A date that is both a weekend and a public holiday is excluded only once, so the totals do not double-count it.
May 1 through May 9, 2025
- • Monday through Friday schedule
- • Both boundary dates included
- • South Korean holidays excluded
- 1. 9 calendar dates evaluated
- 2. 2 weekend dates excluded
- 3. May 5 and the May 6 substitute holiday excluded
The selected range contains 5 business days.
How to read the result
- Contract and administrative rules can differ on whether the starting date counts, so confirm the boundary option first.
- Adding organization-specific closures makes the result closer to the calendar actually used for operations.
Conditions that change the result
- The official snapshot reflects its build-time data and cannot guarantee immediate inclusion of a temporary holiday announced after the latest refresh.
- A date count does not determine cutoff times, time zones, local holidays, or an organization's internal processing rules.
Common input mistakes
- Choosing the wrong base-date inclusion rule can shift an offset result by one business day.
- Leaving the default Monday-to-Friday schedule in place will omit Saturday for a six-day operation.
Reference Knowledge
- ●Range mode includes both boundary dates by default and treats Monday through Friday as working weekdays.
- ●Offset mode excludes the base date by default and begins counting on the next or previous date.
- ●Years covered by the official snapshot use KASI public, substitute, election, and temporary holiday data.
- ●Years unavailable from the API use rule-based fallback, and organization-specific closures can be added manually.
- ●The holiday API is called only when refreshing the snapshot. Visitor calculations run in the browser, and entered dates are not sent to a server.
FAQ
Q.What is the difference between a business day and a calendar day?
Calendar days include every date. Business days include only selected working weekdays after public holidays and custom closure dates have been removed.
Q.Are the start and end dates included?
You can include or exclude each boundary independently. An included boundary still does not count as a business day when it is a non-working weekday or holiday.
Q.Does the base date count when adding 10 business days?
Not by default. Counting begins on the following or preceding date. Turn on the base-date option when the base date itself should be business day one.
Q.Can I calculate a six-day operating week?
Yes. Select Saturday as a working weekday and clear any weekday on which the organization is normally closed.
Q.Are every temporary holiday and election date included automatically?
Public, substitute, election, and temporary holidays present in the latest official KASI snapshot are included automatically. A date announced after that refresh can be absent until the next update, so verify critical dates and add any missing closure manually.
Q.Can a bank or delivery company use a different business calendar?
Yes. Financial institutions, carriers, agencies, and companies may have their own closures and cutoff times. Use this result for planning and confirm actual service availability with the organization.
