WEEKDAY Function in Microsoft Excel: Syntax, Examples & Compatibility
Learn how to convert a date into a weekday number to drive scheduling rules in Microsoft Excel. Includes syntax, two verified-by-reasoning results, troubleshooting and portability notes.
Verification status: Official documentation referenced; example outcomes independently reasoned or arithmetically checked where stated. Not executed in Microsoft Excel. How formula examples are checked
Quick answer: convert a date into a weekday number to drive scheduling rules in Microsoft Excel. The reproducible examples below use explicit values so the formula’s meaning is testable without a large workbook.
Evidence: The function name and syntax are documented in the linked vendor function reference. Expected outputs were independently reasoned or checked outside the application. These are not native Microsoft Excel test results. A guide being published here does not certify every software release or file-import scenario.
Syntax and arguments
=WEEKDAY(serial_number, [return_type])
serial_number is the date; the optional return_type determines numbering. With type 2, Monday is 1 and Sunday is 7.
Best use case: Convert a date into a weekday number to drive scheduling rules.
Set up the example sheet
These examples use DATE to avoid interpreting ambiguous typed date strings. Display their answers as plain numbers.
Enter the formula in an unused cell. For a formula returning several values, leave an unobstructed area where those values can expand. These formulas use comma argument separators in a typical English-language locale; commas or semicolons inside quoted text are data, not argument separators. Adapt the separator if your regional settings require it.
Worked example 1: WEEKDAY with known input
=WEEKDAY(DATE(2026,6,1),2)
Expected output: 1.
1 June 2026 is Monday; return type 2 numbers Monday as 1.
Worked example 2: a second WEEKDAY case
=WEEKDAY(DATE(2026,6,7),2)
Expected output: 7.
7 June 2026 is Sunday, the final day under Monday-first numbering.
Compare both results before replacing literal values or short sample ranges with your own workbook data. For a spilling formula, compare every output cell, not only the top-left result.
Practical advice and troubleshooting
When this formula helps: Explicitly specify the numbering mode; leaving it out normally numbers Sunday as 1, which can reverse a Monday-first business rule.
Important edge case: WEEKDAY is a day-of-week number, not a week-of-year number. Use WEEKNUM or ISOWEEKNUM for week numbers.
If the result differs, first verify the text-versus-number types of the input cells, the argument separators for your locale, and the range size. For dynamic arrays, inspect occupied cells in the output area. An error that looks like a missing function may reflect a software version rather than incorrect data.
Compatibility and version considerations
The shared type-2 examples use a standard numbering convention; other return-type values must be checked against the target program.
Check your installed release for availability and dynamic-array support.
Function availability and parameter behavior must be judged for the specific application and release; a function documented in one spreadsheet does not automatically work in another.
Related guides and official documentation
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Microsoft Excel documentation for WEEKDAY — function syntax and current vendor information.
Editorial verification: Vendor catalogue referenced as of 2026-10-12. The two example outputs are independently reasoned; no native application run, screenshot, or version-specific output is claimed. Review the editorial testing standards if you require stronger proof before importing a workbook.