See Chip's site for an ISO weeknumber formula.
http://www.cpearson.com/excel/weeknum.htm

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HTH

Bob Phillips

"sam" wrote in message
...
using excel 2003 on xpSp2. i'm aware that MS says its normal that jan 1
is
week 1 when you're using the weeknum function. (in this year.only 1 day
in
week1).. how does one modify this so that week 1 of the weeknum function
is
the first 4 day week.. is there a mod i need to apply?