I need help to create a function to determine the week number based on these 2 parameters: Starting date Specified date For example, if I specify April 7, 2010 as the starting date & passed April 20, 2010 as the date to lookup, I would like the function to return WEEK 2. Another example, if I set March 6, 2010 as starting date and looked up April 5, 2010 then it should return WEEK 6. I appreciate your time and help.