WEEKDAY()
Returns which day of the week a date falls on, as a number.
WEEKDAY(serial_number, [return_type])WEEKDAY returns a number representing the day of the week for serial_number. By default, 1 means Sunday through 7 means Saturday.
return_type shifts that numbering — type 2 makes Monday = 1 through Sunday = 7, and type 3 makes Monday = 0 through Sunday = 6 — to match however your workbook counts the week.
It's commonly used inside IF logic or conditional formatting to flag weekends, or to build custom scheduling formulas alongside WORKDAY and NETWORKDAYS.
Arguments
- serial_number
- The date to check.
- return_typeoptional
- Which numbering system to use for the days of the week. Defaults to 1 (Sunday = 1).
Examples
=WEEKDAY("3/16/2026")March 16, 2026 is a Monday, which is day 2 under the default Sunday-first numbering.
=IF(WEEKDAY(A2,2)>5,"Weekend","Weekday")Uses Monday-based numbering (return_type 2) to flag Saturday and Sunday.
WEEKDAY tricks, tips, and workbook hacks
WEEKDAY is easier to remember when you learn the small patterns around it: where it fits, what can break it, and how to combine it with neighboring functions.
Use these practical notes as a working checklist before putting the formula into a real report, model, dashboard, tracker, or reusable template.
Quick wins before you trust the result
- Start with the simplest WEEKDAY formula that answers the question, then add conditions or error handling only when needed.
- Keep input ranges consistent in size, shape, and meaning.
- Test the formula on one row or one small sample before filling it down a large workbook.
- Add a note beside important formulas explaining what business question they answer.
- Pair the formula with related checks so mistakes are easier to spot.
| Trick or hack | Formula pattern | Best use | Watch out |
|---|---|---|---|
| Build the formula in layers | WEEKDAY(serial_number, [return_type]) | When the full formula feels hard to read or debug. | Confirm each argument or nested function before combining everything. |
| Use structured references | =WEEKDAY(Table1[Column]) | Excel Tables make formulas easier to read and expand automatically. | Rename table columns carefully so formulas remain clear. |
| Protect against bad input | =IFERROR(WEEKDAY(...),"Check input") | Dashboards and shared templates where users need a readable message. | Do not hide errors until you understand why they happen. |
| Document the expected result | Add a note or nearby label | Reusable workbooks, finance models, templates, and handoff files. | A clever formula without context becomes expensive to maintain. |
| Mistake | What it looks like | Fix |
|---|---|---|
| Using a wider range than intended | The result changes unexpectedly after new rows or helper columns are added. | Use Excel Tables or named ranges to make the intended input explicit. |
| Mixing text, numbers, dates, and blanks | The answer technically works but does not match the business meaning. | Clean and validate the source column before applying the function. |
| Copying a formula with moving references | The first row works; later rows drift into the wrong range. | Use absolute references, structured references, or named ranges where needed. |
| Scenario | Use | Avoid |
|---|---|---|
| You need a quick answer from clean data | WEEKDAY with the smallest clear range | Overbuilding the formula with unnecessary wrappers |
| The result will appear in a dashboard | Add checks, labels, and readable fallbacks | Leaving raw errors or unexplained blanks for viewers |
| The workbook will grow over time | Excel Tables, named ranges, or structured references | Hard-coded ranges that miss new rows |
| The data comes from another system | Clean inputs before summarizing or transforming | Assuming pasted data has correct types and spacing |
Practice drills
- Write WEEKDAY once with direct cell references and once with an Excel Table reference.
- Break the formula on purpose, then use the error message to identify which argument failed.
- Create a small before/after example that explains the formula to another learner.
