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How to get the ISO week number from a date in Excel and Google Sheets
Excel & Google Sheets
=WEEKNUM(B2,2)✓
Verified example
Computed by a real spreadsheet engine on the sample data below.
| Date | ISO Week Number |
| 2023-12-31 | 1 |
| 2024-01-01 | 1 |
| 2024-01-02 | 2 |
| 2024-01-03 | 2 |
=WEEKNUM(B2,2)→53
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Step by step
- 1Enter your date in cell B2 of your spreadsheet.
- 2In cell C2, input the formula provided for Excel or Google Sheets.
- 3Press Enter to see the ISO week number corresponding to the date in B2.
Tips
- Ensure your date format is recognized by Excel or Google Sheets to avoid errors.
- The second parameter in WEEKNUM (set to 2) specifies the system where weeks start on Monday and the first week of the year includes January 4.
- Check your locale settings as they can affect date interpretation.
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Frequently asked
What does the second parameter in the WEEKNUM function mean?
The second parameter specifies the day of the week that the week begins on and the numerical value of the first week of the year.
Why do I get different results compared to other week number functions?
Different functions like ISO.WEEKNUM or YEARWEEK might use different standards for calculating the week number.
Can I use this formula for dates before 1900?
Excel has limitations with dates before 1900, but Google Sheets supports dates back to 1899-12-30.