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How to get the week number from a date in Excel and Google Sheets
Excel & Google Sheets
=WEEKNUM(A2,2)Try it with your data
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Step by step
- 1Enter your date in A2.
- 2Enter =WEEKNUM(A2,2) in a result cell.
- 3The second argument sets the first day of the week: 1=Sunday, 2=Monday (ISO standard).
- 4For strict ISO 8601 week numbers use =ISOWEEKNUM(A2) in Excel 2013+ or Google Sheets.
- 5WEEKNUM returns 1-53; results may differ slightly from ISO by a week at year boundaries.
Tips
- ISOWEEKNUM and WEEKNUM(date,21) both return ISO 8601 week numbers and are the most globally compatible. Use these for international reporting.
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Frequently asked
What is the difference between WEEKNUM and ISOWEEKNUM?
WEEKNUM starts counting with the week containing January 1. ISOWEEKNUM follows ISO 8601, where week 1 is the week containing the first Thursday of the year. Results differ at year-start and year-end.
How do I group data by week in a pivot table?
Add a helper column with =WEEKNUM(A2) or =ISOWEEKNUM(A2), then use that column as a row field in your pivot table to group records by week number.