Date and Time
The result is a date number that can be formatted as a date. You then see the date of a day that is a certain number of workdays away from the start date.
WORKDAY(StartDate; Days; Holidays)
StartDate is the date from when the calculation is carried out. If the start date is a workday, the day is included in the calculation.
Days is the number of workdays. Positive value for a result after the start date, negative value for a result before the start date.
Holidays is a list of optional holidays. These are non-working days. Enter a cell range in which the holidays are listed individually.
When entering dates as part of formulas, slashes or dashes used as date separators are interpreted as arithmetic operators. Therefore, dates entered in this format are not recognized as dates and result in erroneous calculations. To keep dates from being interpreted as parts of formulas use the DATE function, for example, DATE(1954;7;20), or place the date in quotation marks and use the ISO 8601 notation, for example, "1954-07-20". Avoid using locale dependent date formats such as "07/20/54", the calculation may produce errors if the document is loaded under different locale settings.
Unambiguous conversion is possible for ISO 8601 dates and times in their extended formats with separators. If a #VALUE! error occurs, then unselect Generate #VALUE! error in Tools > Options > LibreOffice Calc > Formula, button Details... in section "Detailed Calculation Settings", Conversion from text to number list box.
What date came 17 workdays after 1 December 2001? Enter the start date "2001-12-01" in C3 and the number of workdays in D3. Cells F3 to J3 contain the following Christmas and New Year holidays: "2001-12-24", "2001-12-25", "2001-12-26", "2001-12-31", "2002-01-01".
=WORKDAY(C3;D3;F3:J3) returns 2001-12-28. Format the serial date number as a date, for example in the format YYYY-MM-DD.