How to Change Excel Week Numbers to a Monday-Starting Week
Question details
The user needs to configure spreadsheet formulas to calculate week numbers and weekdays starting on Monday rather than the default Sunday.
- Product
- Excel
- Device & OS
- not provided
- Scenario
- Calculating accurate week numbers for scheduling, payroll, or project management where the operational work week strictly begins on Monday.
- Observed behavior
- Excel defaults to Sunday as the first day of the week for date functions, yielding incorrect week and day numbers for Monday-starting requirements.
Determine whether your spreadsheet requires standard Monday-starting week numbers or the official ISO 8601 week-date system, as different functions apply to each scenario.
Use the WEEKNUM Function with a Return Type
The most direct way to change the week start day to Monday for a specific cell formula.
Excel does not have a global file-level setting to change the starting day of the week for all formulas. Instead, you must specify Monday as the starting day directly within the function using the return type argument.
Click on the empty cell where you want the calculated week number to be displayed.
Type the formula =WEEKNUM(B3, 2), replacing 'B3' with the cell reference that contains your target date.
Press Enter. The '2' in the second argument instructs the function to start the week on Monday.
Use the ISOWEEKNUM Function for ISO Standards
Ideal for European businesses and international projects that follow the ISO 8601 week numbering system.
Adjust the WEEKDAY Function for Monday Starts
Use this method if you need to return the specific day of the week (1 through 7) rather than the week number of the year.
Calculate Dates and Week Numbers Easily in WPS Spreadsheet
WPS Spreadsheet provides full support for advanced date and time functions, including WEEKNUM and ISOWEEKNUM, allowing you to easily adjust work week calculations without modifying system settings.
- 1. Open your file in WPS Spreadsheet: Launch WPS Office and open the worksheet containing your dates.
- 2. Start the formula: Click your target cell, type =WEEKNUM(, and select the cell containing your date.
- 3. Add the Monday return type: Type , 2) immediately after the cell reference and press Enter to complete the calculation.
Frequently Asked Questions
Can I change the default start of the week for the entire Excel file?
No, Excel does not have a workbook-level setting to change the default start of the week. Changing your computer's regional settings affects the entire OS and all applications, not just the workbook. You must specify the return type argument in individual functions like WEEKNUM or WEEKDAY.
What is the difference between WEEKNUM and ISOWEEKNUM?
WEEKNUM calculates weeks based on January 1st starting week 1, while ISOWEEKNUM follows the ISO 8601 standard where week 1 is the week containing the first Thursday of the year. Furthermore, ISOWEEKNUM strictly designates Monday as the first day of the week by default.
Why does my week number calculation seem off by one week?
This usually happens if you are using the standard WEEKNUM function for a business requirement that actually follows the ISO system. If your company uses ISO standards, switch your formulas from =WEEKNUM(cell, 2) to =ISOWEEKNUM(cell) to accurately align the calculations.
