How to show week number columns in a Microsoft Project schedule

There are times when you would like to show the week number of dates in a Microsoft Project schedule, for example, when dealing with supply chain long lead items tasks. 

In this tutorial, we are going to use 2 text custom fields to display the week numbers of Start and Finish dates. This tutorial makes the following assumptions:

1. First day of the week is Sunday

2. First and last week of the year must have at least 4 days to count as full week

Here are 3 sets of formulas for

1. Week number with no text prefix (i.e. 10)

   • Start Week No. = DatePart("ww", [Start], 1 ,2)

   • Finish Week No. = DatePart("ww", [Finish], 1 ,2)

2. Week number with the text prefix “week” (i.e. week 10)

   • Start Week No. = “Week " & DatePart("ww", [Start], 1, 2)

   • Finish Week No. = “Week " & DatePart("ww", [Finish], 1, 2)

3. Week number with the prefixes’ year and text “week” (i.e. 2020 week 10)

   1. Start Week No. = IIf(DatePart("y",[Start])>362 And DatePart("ww",[Start],1,2)=1,Year([Start])+1 & " week " & DatePart("ww",[Start],1,2),IIf(DatePart("y",[Start])<4 And DatePart("ww",[Start],1,2)>51,Year([Start])-1 & " week " & DatePart("ww",[Start],1,2),Year([Start]) & " week " & DatePart("ww",[Start],1,2)))

   2. Finish Week No. = IIf(DatePart("y",[Finish])>362 And DatePart("ww",[Finish],1,2)=1,Year([Finish])+1 & " week " & DatePart("ww",[Finish],1,2),IIf(DatePart("y",[Finish])<4 And DatePart("ww",[Finish],1,2)>51,Year([Finish])-1 & " week " & DatePart("ww",[Finish],1,2),Year([Finish]) & " week " & DatePart("ww",[Finish],1,2)))

If you need a step by step guide or an explanation of these 3 sets of formulas, then watch the video below.

For more information about DatePart, check out these references from Microsoft

1. Project functions for custom fields in Project desktop

2. DatePart function