Master the WEEKDAY Function: Extract Day Names from Dates in Excel
=WEEKDAY(serial_number, [return_type])The WEEKDAY function is one of Excel's most practical date and time utilities, designed to extract the day of the week from any given date. Whether you're managing project schedules, analyzing customer behavior patterns, or organizing business calendars, understanding how to use WEEKDAY will significantly enhance your data analysis capabilities. This function returns a numeric value representing the day of the week, making it incredibly useful for conditional formatting, scheduling automation, and business intelligence dashboards. The beauty of WEEKDAY lies in its flexibility and simplicity. By using different return_type parameters, you can customize how the function displays results—whether you prefer numbers 1-7, 0-6, or even 1-7 with Monday as the starting day. This adaptability makes WEEKDAY compatible with various international business standards and regional preferences. Learning to combine WEEKDAY with other Excel functions opens doors to sophisticated scheduling solutions, automated reporting systems, and intelligent data filtering mechanisms that can save hours of manual work.
Syntax & Parameters
The WEEKDAY function operates with a straightforward but powerful syntax: =WEEKDAY(serial_number, [return_type]). The serial_number parameter is mandatory and represents the date you want to analyze. This can be entered as a date value, a cell reference containing a date, or a date returned by another function like TODAY() or DATE(). Excel recognizes dates as serial numbers internally, where January 1, 1900 equals 1. The return_type parameter is optional but crucial for customizing your results. When omitted, it defaults to 1, returning values 1-7 where Sunday equals 1 and Saturday equals 7. Setting return_type to 2 returns 1-7 with Monday as day 1, following ISO 8601 standards preferred in many European countries. Using return_type 3 returns 0-6 with Monday as day 0, useful for programming logic and modulo operations. Understanding these options ensures your formula aligns with your specific business requirements and regional conventions. Pro tip: Always verify your return_type setting matches your intended use case to avoid scheduling conflicts or misaligned reports.
serial_numberreturn_typePractical Examples
Identifying Weekend Dates for Project Scheduling
=IF(WEEKDAY(A2)>5,"Weekend","Weekday")This formula checks if the date in cell A2 returns a WEEKDAY value greater than 5 (Friday=5, Saturday=6, Sunday=7). If true, it displays 'Weekend', otherwise 'Weekday'. This helps automatically flag dates requiring special handling or alternative scheduling.
Extracting Day Names for Customer Communication
=TEXT(A2,"DDDD")While TEXT is used here instead of WEEKDAY alone, combining WEEKDAY with TEXT provides readable output. Alternatively, use =CHOOSE(WEEKDAY(A2),"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday") for the same result without TEXT formatting.
Calculating Business Day Surcharges
=IF(WEEKDAY(A2,2)>5,BASE_RATE*1.25,BASE_RATE)Using return_type 2 (Monday=1), this formula checks if the weekday number exceeds 5 (Saturday=6, Sunday=7). If the delivery falls on a weekend, it applies a 25% surcharge to the base rate. The return_type 2 is chosen here because it's more intuitive for business logic where weekdays are numbered 1-5.
Key Takeaways
- WEEKDAY extracts the day of the week from any date, returning numeric values 1-7 based on the selected return_type parameter.
- Return_type selection is critical: use 1 for Sunday-start (American), 2 for Monday-start (ISO 8601 international), or 3 for zero-based indexing (programming).
- Combine WEEKDAY with TEXT, CHOOSE, IF, or SUMIF functions to create powerful scheduling automation, conditional formatting, and business intelligence solutions.
- WEEKDAY is compatible across all modern Excel versions (2007-365), Google Sheets, and LibreOffice, making it essential for cross-platform data analysis.
- Performance optimization through helper columns and proper formula structure ensures WEEKDAY remains efficient even in large datasets with thousands of date calculations.
Pro Tips
Use return_type 2 for international business applications and ISO 8601 compliance, making your formulas more compatible with global teams and reducing confusion about day numbering conventions.
Impact : Prevents scheduling conflicts and misaligned reports when working with international partners or migrating data to different systems.
Combine WEEKDAY with AGGREGATE function to exclude errors when analyzing date ranges with missing or corrupted data: =AGGREGATE(12,5,WEEKDAY(A2:A100))
Impact : Enables robust data analysis that doesn't break when encountering invalid dates, improving reporting reliability.
Cache WEEKDAY results in a helper column rather than recalculating in complex formulas, especially in large datasets. This dramatically improves spreadsheet performance and makes debugging easier.
Impact : Reduces calculation time by 50-70% in large workbooks and makes formulas more readable and maintainable.
Create a lookup table mapping WEEKDAY results to business rules (weekend premium rates, staffing levels, delivery availability) instead of nesting multiple IF statements.
Impact : Simplifies formula maintenance, reduces errors, and makes business logic changes easier without editing complex nested formulas.
Useful Combinations
Automated Weekend Flagging with Conditional Formatting
=WEEKDAY(A2)>5Use this formula as the condition for conditional formatting to automatically highlight weekend dates in your calendar or schedule. Apply formatting rules that change cell background color to red for weekends, making visual identification instant and reducing scheduling errors.
Dynamic Staffing Requirements Based on Day of Week
=IF(WEEKDAY(A2,2)<=5,STANDARD_STAFF,WEEKEND_STAFF)Combine WEEKDAY with IF statements to automatically assign different staffing levels based on whether a date falls on a weekday or weekend. This enables dynamic workforce planning and budget allocation that adjusts automatically as dates change.
Revenue Analysis by Day of Week Pattern
=SUMIF(WEEKDAY(DATE_RANGE,2),3,REVENUE_RANGE)Use WEEKDAY within SUMIF to aggregate revenue data by specific day of the week (in this case, Wednesday=3). This reveals patterns in customer behavior, helping identify which days generate the most revenue and informing marketing and staffing decisions.
Common Errors
Cause: The serial_number parameter contains text that Excel cannot interpret as a valid date, or the return_type parameter is not a number between 1 and 3.
Solution: Verify the date format in your cell is recognized by Excel as a date (right-click, Format Cells, check Date category). Use DATE() function to create dates programmatically. Ensure return_type is 1, 2, or 3 only.
Cause: The return_type parameter is outside the valid range (1-3), or the serial_number is a negative value or exceeds Excel's date limits (before 1/1/1900 or after 12/31/9999).
Solution: Always use return_type values of 1, 2, or 3 only. Verify your date is within Excel's valid date range. Use IF statements to validate dates before passing to WEEKDAY: =IF(AND(A2>0,A2<44562),WEEKDAY(A2),"Invalid Date")
Cause: The cell reference in the serial_number parameter points to a deleted column or row, or the formula references a sheet that no longer exists.
Solution: Check that all cell references are valid and point to existing cells. Use the Name Manager to verify named ranges. Restore deleted columns/rows if necessary or update the formula with correct references.
Troubleshooting Checklist
- 1.Verify the date in serial_number is formatted as a date, not text. Check Format Cells to confirm Date category is applied.
- 2.Confirm return_type parameter is either 1, 2, or 3. Other values will generate #NUM! error.
- 3.Test with a known date like TODAY() to verify WEEKDAY is functioning before troubleshooting complex formulas.
- 4.Check for hidden spaces or special characters in date cells that might prevent Excel from recognizing the value as a date.
- 5.Verify the date falls within Excel's valid range (1/1/1900 to 12/31/9999). Dates outside this range will cause errors.
- 6.Ensure you're using consistent return_type throughout related formulas to avoid confusion and incorrect day-of-week identification.
Edge Cases
Leap year dates (February 29)
Behavior: WEEKDAY correctly identifies the day of the week for leap year dates. For example, February 29, 2024 (Thursday) returns 5 with return_type 1.
Solution: No special handling needed; WEEKDAY automatically accounts for leap years.
Excel's date system inherently handles leap years, so WEEKDAY works seamlessly.
Dates before 1900 or after 9999
Behavior: WEEKDAY returns #NUM! error for dates outside Excel's valid range (1/1/1900 to 12/31/9999).
Solution: Use IF statement to validate: =IF(AND(A2>=DATE(1900,1,1),A2<=DATE(9999,12,31)),WEEKDAY(A2),"Out of Range")
This is a fundamental Excel limitation, not specific to WEEKDAY.
Decimal or fractional dates (time component)
Behavior: WEEKDAY ignores the time component and processes only the date portion. For example, 1/15/2024 14:30 (2:30 PM) returns the same WEEKDAY result as 1/15/2024 00:00.
Solution: No action needed; WEEKDAY automatically handles date-time values correctly by extracting only the date component.
This is actually a useful feature for date-time stamps where only the day of week matters.
Limitations
- •WEEKDAY processes single dates only and cannot directly analyze date ranges without array formulas or helper columns. For bulk processing, copy the formula down or use array formula syntax in Excel 365.
- •The function returns only numeric day-of-week values; it cannot directly return day names. You must combine it with TEXT, CHOOSE, or other functions to display readable day names, adding formula complexity.
- •WEEKDAY is limited to Excel's date range (1/1/1900 to 12/31/9999) and cannot process historical dates before 1900 or future dates beyond 9999, restricting use in specialized historical or futuristic analyses.
- •Different return_type conventions across systems (Excel uses 1-3, Google Sheets uses 'mode' parameter with different naming) can cause confusion when migrating formulas between platforms, requiring careful syntax verification.
Alternatives
Compatibility
✓ Excel
Since 2007
=WEEKDAY(serial_number, [return_type]) - Fully supported in Excel 2007, 2010, 2013, 2016, 2019, and 365 with identical syntax and functionality.✓Google Sheets
=WEEKDAY(date, [mode]) - Google Sheets uses 'mode' instead of 'return_type' but functions identically. Mode 1=Sunday-start, Mode 2=Monday-start, Mode 3=zero-based.Fully compatible with Google Sheets. Formulas can be copied between Excel and Google Sheets without modification.
✓LibreOffice
=WEEKDAY(serial_number, [mode]) - LibreOffice Calc supports WEEKDAY with identical functionality to Excel. Mode parameter works the same as return_type.