NETWORKDAYS.INTL
Returns the number of workdays between a start date and an end date. There are options to define weekend days and holidays. The optional weekend parameter (or a string) can be used to define the weekend days (or the nonworking days in each week). Also, optionally, the user can define a holiday list. The weekend days and userdefined holidays are not counted as working days.
NETWORKDAYS.INTL(StartDate; EndDate [; [ Weekend ] [; 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.
EndDate is the date up until when the calculation is carried out. If the end date is a workday, the day is included in the calculation.
Weekend is an optional parameter â€“ a number or a string used to specify the days of the week that are weekend days and are not considered working days. Weekend is a weekend number or string that specifies when weekends occur. Weekend number values indicate the following weekend days:
Number 1 to 7 for twoday weekends and 11 to 17 for oneday weekends.
Number

Weekend

1 or omitted

Saturday and Sunday

2

Sunday and Monday

3

Monday and Tuesday

4

Tuesday and Wednesday

5

Wednesday and Thursday

6

Thursday and Friday

7

Friday and Saturday

11

Sunday only

12

Monday only

13

Tuesday only

14

Wednesday only

15

Thursday only

16

Friday only

17

Saturday only

Weekend string provides another way to define the weekly nonworking days. It must have seven (7) characters â€“ zeros (0) for working day and ones (1) for nonworking day. Each character represents a day of the week, starting with Monday. Only 1 and 0 are valid. â€ś1111111â€ť is an invalid string and should not be used. For example, the weekend string â€ś0000011â€ť defines Saturday and Sunday as nonworking days.
Holidays is an optional list of dates that must be counted as nonworking days. The list can be given in a cell range.
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, "19540720". 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 LibreOffice  PreferencesTools  Options  LibreOffice Calc  Formula, button Details... in section "Detailed Calculation Settings", Conversion from text to number list box.
This function ignores any text or empty cell within a data range. If you suspect wrong results from this function, look for text in the data ranges. To highlight text contents in a data range, use the value highlighting feature.
How many workdays fall between December 15, 2016 and January 14, 2017? Let the start date be located in C3 and the end date in D3. Cells F3 to J3 contain five (5) holidays for Christmas and New Year in date format: December 24, 2016; December 25, 2016; December 26, 2016; December 31, 2016; and January 1, 2017.
=NETWORKDAYS.INTL(C3;D3;;F3:J3) returns 21 workdays with default for weekend days.
=NETWORKDAYS.INTL(C3;D3;11;F3:J3) returns 24 workdays with Sunday only weekends.
Alternatively, use the weekend string â€ś0000001â€ť to define Sunday as the nonworking day of every week.
=NETWORKDAYS.INTL(C3;D3;â€ś0000001â€ť;F3:J3) returns 24 workdays with Sunday only weekend.
The function can be used without the two optional parameters â€“ weekday and holidays â€“ by leaving them out:
=NETWORKDAYS.INTL(C3;D3) gives 22 working days.
This function is available since LibreOffice 4.3.
This function is not part of the Open Document Format for Office Applications (OpenDocument) Version 1.3. Part 4: Recalculated Formula (OpenFormula) Format standard. The name space is
COM.MICROSOFT.NETWORKDAYS.INTL