Hi ciccio

You are using ISO weeknumbers, See

http://www.cpearson.com/excel/weeknum.htm
And
http://www.rondebruin.nl/weeknumber.htm



--
Regards Ron de Bruin
http://www.rondebruin.nl



"ciccio" wrote in message ...
Excel gives an incorrect calendard week number.
=num.week(A1) gives 4 if in A1 is 21/01/05. Actually 21/01/05 is in week 3!
Why? and more important , may I correct it?