COUPDAYS

Quirk found

Category: Financial · Last tested 2026-09-01

Real compatibility results for the COUPDAYS function: executed in Excel for the web, Google Sheets and LibreOffice Calc, with desktop Excel behavior from Microsoft’s official documentation (we do not run desktop Excel — Excel for the web is a different application and is executed separately). Syntax and links to that documentation are below.

Support matrix

Engine	Documented	Live-tested	Verdict
Excel (desktop)	Yes	No — documented only	n/a
Excel for the web	—	Yes (recalc, 2026-09-01)	Supported, behaves as documented
Google Sheets	Yes	Yes (Drive import, 2026-08-31)	Supported, behaves as documented
LibreOffice Calc	Yes	Yes (25.8.7.3, 2026-08-31)	Quirk found

LibreOffice version history

We executed the same test cases under each LibreOffice release to show exactly when COUPDAYS’s support changed — not documentation claims, real results.

LibreOffice version	Verdict	Tested
24.2.0.3	Quirk found	2026-08-31
24.8.7.2	Quirk found	2026-08-31
25.2.0.3	Quirk found	2026-08-31
25.8.7.3	Quirk found	2026-08-31

Why isn't COUPDAYS working in LibreOffice?

COUPDAYS exists in LibreOffice 25.8.7.3, but it is not a drop-in match for Excel — our executed tests found real behavioral differences (detailed in the test results on this page). If a formula that works in Excel or Google Sheets misbehaves in LibreOffice, compare your usage against the failing cases above before assuming your data is wrong.

Discovered quirks

=COUPDAYS(A2,A3,3,A5) on LibreOffice Calc returned #VALUE!, but the documented/expected result is #NUM!.
Provenance
Excel documents: "If frequency is any number other than 1, 2, or 4, COUPDAYS returns the #NUM! error value."; MISMATCH vs expected: expected '#NUM!', got '#VALUE!'
=COUPDAYS(A2,A3,A4,-1) on LibreOffice Calc returned #VALUE!, but the documented/expected result is #NUM!.
Provenance
Excel documents: "If basis < 0 or if basis > 4, COUPDAYS returns the #NUM! error value."; MISMATCH vs expected: expected '#NUM!', got '#VALUE!'
=COUPDAYS(A3,A2,A4,A5) on LibreOffice Calc returned #VALUE!, but the documented/expected result is #NUM!.
Provenance
Excel documents: "If settlement >= maturity, COUPDAYS returns the #NUM! error value."; MISMATCH vs expected: expected '#NUM!', got '#VALUE!'

Executed test cases

Excel for the web (executed 2026-09-01 via OneDrive recalculation)

These values come from Excel for the web, not from desktop Excel. They are two different implementations of the calculation engine, and this run measured only the web one: the corpus was uploaded to OneDrive as .xlsx, recalculated by Excel for the web on open, and downloaded again for readback. Excel for the web is a rolling service with no pinnable version, so the run is identified by its date. Where a value here disagrees with the Expected column — which is Microsoft’s documentation of the desktop product — we cannot tell you whether the web engine diverges from the desktop one or the documentation is wrong about both, because we do not run desktop Excel.

Formula	Description	Result	Expected	Verdict
=COUPDAYS(A2,A3,A4,A5)	Microsoft's documented worked example: length of the coupon period containing settlement, semiannual, actual/actual	181	181 Provenance Microsoft's page publishes this example's result as 181. Setup serials are the dates Microsoft's page prints: 40568 = 2011-01-25 (settlement), 40862 = 2011-11-15 (maturity), frequency 2 (semiannual), basis 1 (actual/actual). Counting coupon dates back from maturity in six-month steps gives 2011-11-15, 2011-05-15, 2010-11-15, so the settlement date falls in the coupon period 2010-11-15 to 2011-05-15. On basis 1 the length of that period is the actual day count from 2010-11-15 to 2011-05-15, which Python date subtraction gives as 181 days	Matched
=COUPDAYS(A2,A3,A4,0)	The same bond on the US (NASD) 30/360 basis instead of actual/actual	180	180 Provenance On any 30/360 basis a year is exactly 360 days, so a semiannual coupon period is 360/2 = 180 days regardless of the calendar -- one day fewer than the actual/actual 181 for this particular period. This case discriminates the basis argument, which the documented example alone does not	Matched
=COUPDAYS(A2,A3,3,A5)	A frequency of 3, which is not one of the permitted values	#NUM!	#NUM! Provenance Excel documents: "If frequency is any number other than 1, 2, or 4, COUPDAYS returns the #NUM! error value."	Matched
=COUPDAYS(A2,A3,A4,-1)	A negative day-count basis	#NUM!	#NUM! Provenance Excel documents: "If basis < 0 or if basis > 4, COUPDAYS returns the #NUM! error value."	Matched
=COUPDAYS(A3,A2,A4,A5)	Settlement and maturity swapped, so settlement is after maturity	#NUM!	#NUM! Provenance Excel documents: "If settlement >= maturity, COUPDAYS returns the #NUM! error value."	Matched

Google Sheets (executed 2026-08-31 via Drive import)

Google Sheets is a rolling service with no pinnable version, so this run is identified by its date. The corpus was imported to Drive as .xlsx, recalculated by Sheets, and exported back for readback.

Formula	Description	Result	Expected	Verdict
=COUPDAYS(A2,A3,A4,A5)	Microsoft's documented worked example: length of the coupon period containing settlement, semiannual, actual/actual	181	181 Provenance Microsoft's page publishes this example's result as 181. Setup serials are the dates Microsoft's page prints: 40568 = 2011-01-25 (settlement), 40862 = 2011-11-15 (maturity), frequency 2 (semiannual), basis 1 (actual/actual). Counting coupon dates back from maturity in six-month steps gives 2011-11-15, 2011-05-15, 2010-11-15, so the settlement date falls in the coupon period 2010-11-15 to 2011-05-15. On basis 1 the length of that period is the actual day count from 2010-11-15 to 2011-05-15, which Python date subtraction gives as 181 days	Matched
=COUPDAYS(A2,A3,A4,0)	The same bond on the US (NASD) 30/360 basis instead of actual/actual	180	180 Provenance On any 30/360 basis a year is exactly 360 days, so a semiannual coupon period is 360/2 = 180 days regardless of the calendar -- one day fewer than the actual/actual 181 for this particular period. This case discriminates the basis argument, which the documented example alone does not	Matched
=COUPDAYS(A2,A3,3,A5)	A frequency of 3, which is not one of the permitted values	#NUM!	#NUM! Provenance Excel documents: "If frequency is any number other than 1, 2, or 4, COUPDAYS returns the #NUM! error value."	Matched
=COUPDAYS(A2,A3,A4,-1)	A negative day-count basis	#NUM!	#NUM! Provenance Excel documents: "If basis < 0 or if basis > 4, COUPDAYS returns the #NUM! error value."	Matched
=COUPDAYS(A3,A2,A4,A5)	Settlement and maturity swapped, so settlement is after maturity	#NUM!	#NUM! Provenance Excel documents: "If settlement >= maturity, COUPDAYS returns the #NUM! error value."	Matched

LibreOffice Calc 25.8.7.3 (tested 2026-08-31)

Formula	Description	Result	Expected	Verdict
=COUPDAYS(A2,A3,A4,A5)	Microsoft's documented worked example: length of the coupon period containing settlement, semiannual, actual/actual	181	181 Provenance Microsoft's page publishes this example's result as 181. Setup serials are the dates Microsoft's page prints: 40568 = 2011-01-25 (settlement), 40862 = 2011-11-15 (maturity), frequency 2 (semiannual), basis 1 (actual/actual). Counting coupon dates back from maturity in six-month steps gives 2011-11-15, 2011-05-15, 2010-11-15, so the settlement date falls in the coupon period 2010-11-15 to 2011-05-15. On basis 1 the length of that period is the actual day count from 2010-11-15 to 2011-05-15, which Python date subtraction gives as 181 days	Matched
=COUPDAYS(A2,A3,A4,0)	The same bond on the US (NASD) 30/360 basis instead of actual/actual	180	180 Provenance On any 30/360 basis a year is exactly 360 days, so a semiannual coupon period is 360/2 = 180 days regardless of the calendar -- one day fewer than the actual/actual 181 for this particular period. This case discriminates the basis argument, which the documented example alone does not	Matched
=COUPDAYS(A2,A3,3,A5)	A frequency of 3, which is not one of the permitted values	#VALUE!	#NUM! Provenance Excel documents: "If frequency is any number other than 1, 2, or 4, COUPDAYS returns the #NUM! error value."	Mismatch
=COUPDAYS(A2,A3,A4,-1)	A negative day-count basis	#VALUE!	#NUM! Provenance Excel documents: "If basis < 0 or if basis > 4, COUPDAYS returns the #NUM! error value."	Mismatch
=COUPDAYS(A3,A2,A4,A5)	Settlement and maturity swapped, so settlement is after maturity	#VALUE!	#NUM! Provenance Excel documents: "If settlement >= maturity, COUPDAYS returns the #NUM! error value."	Mismatch

Docs & syntax

Excel (desktop): official documentation
Google Sheets: official documentation
LibreOffice Calc: official documentation

Where COUPDAYS behaves differently

Bond and treasury functions after a migration: what actually breaks
Executed across 26 fixed-income functions and 161 cases: ODDFPRICE and ODDFYIELD are literal stubs in LibreOffice, TBILLPRICE prices a two-year bill, INTRATE's default basis loses a day, and MDURATION is wrong on actual/actual. 83 of 84 documented #NUM! cases arrive as #VALUE!. Google Sheets matched 127 of 161.