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Rosy_888's avatar
Rosy_888
Copper Contributor
Aug 05, 2021

Weeknum function in Excel

Hello,

By using WEEKNUM("08/03/2021") function in Excel or Google sheet, the result is 32. However, by using https://www.whatisthedatetoday.com/week-numbers-2021.html and other websites, they show that 08/03/2021 is week 31 in 2021. Why are there differences? 

 

 

Thanks,

excel
Excel for web
Formulas and Functions
office 365

1 Reply

  • Riny_van_Eekelen's avatar
    Riny_van_Eekelen
    Platinum Contributor
    Aug 05, 2021

    Rosy_888 By default, WEEKNUM starts counting weeks from the first of January and weeks start on Sunday's. In 2021, January 1st, was on a Friday. Hence, week 1 for 2021 only contains 2 days (Friday, Saturday) with week 2 starting Sunday the 3rd. Another week numbering standard was issued by the ISO and counts full weeks, starting on Mondays. Hence, the first full week of 2021 (=week 1) started Monday, January 4. In Excel, this standard is used by the ISOWEEKNUM function.

     

    With WEEKNUM, you change the outcome by setting one of 10 optional arguments (1 or 2 to choose Sunday or Monday as the first day of the week, 11-17 to choose starting days from Monday to Sunday and 21 to use the ISO standard).

     

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