Excel 2007, weeknum() returning incorrect number

**jakobahman** · 08-12-2009, 10:55 AM

Hi there.

I need to use weeknum() for a number of situations in a project I'm working on.

But when I use =WEEKNUM(DATE(2010;1;31)) it returns 6, instead of 4 as it should. Using it on today's date returns correct number.

I'm clueless as to why...

Any ideas?

**shg** · 08-12-2009, 11:02 AM

See Help for the WEEKNUM function -- the first week is the one that starts on a Saturday or Sunday, possibly in the prior year, and ends in the specified year.

31 Jan would never be in week 4 for any year.

**oldchippy** · 08-12-2009, 11:05 AM

Hi,

More info on WEEK NUMBERING here

http://www.rondebruin.nl/weeknumber.htm

**jakobahman** · 08-13-2009, 03:14 AM

Originally Posted by shg

See Help for the WEEKNUM function -- the first week is the one that starts on a Saturday or Sunday, possibly in the prior year, and ends in the specified year.

31 Jan would never be in week 4 for any year.

Ahh... Where I am from we use the ISO standard, where the week starts with a Monday. And that is why 31 Jan would be on week 4 in 2010(week 1 starts Jan 4th).

Thanks for the link oldshippy, that made it all clear.