=WEEKNUM(DATE(LEFT(A1,4),MID(A1,5,2),RIGHT(A1,2)))

Bur if you need ISO week numbers, read this first

http://www.cpearson.com/excel/weeknum.htm

--
Kind regards,

Niek Otten
Microsoft MVP - Excel

"mark paul" <mark wrote in message ...
| Hello, from a database query I have production dates in format YYYYMMDD (e.g.
| 20070227) I would like to convert this to a weeknumber. How can I do this?
|
| your help is very much appreciated