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WEEKDAY

Quirk found

Category: Date and time · Last tested 2026-07-04

Support matrix

Engine	Documented	Live-tested	Verdict
Excel	Yes	Not yet	n/a
Google Sheets	Yes	Not yet	n/a
LibreOffice Calc	Yes	Yes (24.2.7.2, 2026-07-04)	Quirk found

Discovered quirks

=WEEKDAY(DATE(2008,2,14),99) on LibreOffice Calc returned #VALUE!, but the documented/expected result is #NUM!. Microsoft docs: an invalid return_type raises #NUM!.; MISMATCH vs expected: expected '#NUM!', got '#VALUE!'

Executed test cases

LibreOffice Calc 24.2.7.2 (tested 2026-07-04)

Formula	Description	Result	Expected	Verdict
=WEEKDAY(DATE(2008,2,14))	Default return_type 1: Sunday=1..Saturday=7. Feb 14, 2008 is a Thursday. Source: https://support.microsoft.com/en-us/office/weekday-function-60e44483-2ed1-439f-8bd0-e404c190949a (worked example, WEEKDAY(A2)=5)	5	5	Matched
=WEEKDAY(DATE(2008,2,14),2)	return_type 2: Monday=1..Sunday=7. Source: Microsoft WEEKDAY docs worked example, WEEKDAY(A2,2)=4.	4	4	Matched
=WEEKDAY(DATE(2008,2,14),3)	return_type 3: Monday=0..Sunday=6 (zero-based). Thursday is 3 in this scheme.	3	3 Per Microsoft's return_type table, mode 3 maps Monday..Sunday to 0..6; Thursday (the 4th weekday counting Monday=0) = 3.	Matched
=WEEKDAY(DATE(2008,2,14),12)	return_type 12: Tuesday=1..Monday=7 (ISO-style variant start day). Thursday is the 3rd day in this scheme.	3	3 Per Microsoft's return_type table, mode 12 maps Tuesday=1,Wed=2,Thu=3,...,Monday=7.	Matched
=WEEKDAY(DATE(2008,2,14),16)	return_type 16: Saturday=1..Friday=7. Thursday is the 6th day in this scheme.	6	6 Per Microsoft's return_type table, mode 16 maps Saturday=1,Sun=2,Mon=3,Tue=4,Wed=5,Thu=6,Fri=7.	Matched
=WEEKDAY(DATE(2008,2,14),99)	An out-of-range return_type (not one of the documented 1,2,3,11-17 values) is a documented error condition.	#VALUE!	#NUM! Microsoft docs: an invalid return_type raises #NUM!.	Mismatch

Docs & syntax

Excel: official documentation
Google Sheets: official documentation
LibreOffice Calc: official documentation