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Frequent Visitor

How to calculate week number?

Im creating a small booking app, where the users are used to Weeknumbers.


Is it posible to spesify like :


Week : 5  

Result would be : 30/1-2017 - 5/2-2017


Or vice versa,

Spesify the date and then get the current weeknumber.


This allso has to adjust for leap year.


Best Regards



Thank you @Anonymous,

I was looking for this. I will try it tomorrow 🙂


Advocate I
Advocate I


i am french,i need a formula to calculate week number calendar European.


Best regards,


Thank you dionmills_argos it helped a lot !

This worked great after I replaced all the ";" and replaced them with ",". Also I replace the datapicker with today() to get today's weeknumber.

Not applicable

I've attached my solution for calculating the week number based off of Today().  All the examples looked like fun so I wanted to try my hand as well.  Only minor testing performed but it seems to work.  How it works is:

- Find the number of days between the current date and the first of the year using DateDiff

- Add the day of the week for the first of the year using "WeekDay"

- Divide by 7

- Round Up


RoundUp((DateDiff(DateValue(Concatenate("1/1/", Text(Year(Today())))), Today()) + Value(WeekDay(Concatenate("1/1/", Text(Year(Today())))))))/7,0)

Hello DennisO,

Thank you for sharing.
I copy paste the expression but I receive an error. Are you sure it works? Can you copy paste what you have posted and try it, please?

Weekk number ISO:




selec=datepicker or label

remove ; , if need

Hi AUPowerapps,


It works perfectly ! Thank you !

I am trying to use this formula with a date picker and 1,1 as suggested by you and getting a -ve week value. . . For the first week on tear it is ok. . And in the second week it says "0" and after that -ve. can you please help.

This solution rocks. THX a 1000 times @AUPowerappps 




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