Display Week Number in excel

Question

I am writing a formula to display the WeekNumber in a month, week starting from Monday. But at the month end if the week starts at Monday and following dates are in next month then the week number should be displayed as the next month first week. For example: Week Starts on Monday, so if Monday is 31st Aug and remaining days ie Tue to Sun are in next month then the Week Number should display as 1 and if Monday, Tue, Wed and Thurs are last days of the month and following days ie Friday to Sun are in next month then Week number should be displayed as W5 or that month last week.

i have written a formula but i am unable to satisfy the conditions.

="W"&INT((6+DAY(E2+1-WEEKDAY(E2,2)))/7)

Answer 1

This will be no fun to do using formulas.

In VBA, however, it is not that convoluted using two generic functions:

Public Function WeekOfMonth( _
    ByVal Date1 As Date) _
    As Integer
    
    Dim ThursdayInWeek  As Date
    Dim FirstThursday   As Date
    Dim WeekNumber      As Integer
    
    ThursdayInWeek = DateWeekdayInWeek(Date1, vbThursday, vbMonday)
    FirstThursday = DateWeekdayInMonth(ThursdayInWeek, 1, vbThursday)
    WeekNumber = 1 + DateDiff("ww", FirstThursday, Date1, vbMonday)
    
    WeekOfMonth = WeekNumber
    
End Function

and then:

="W"&WeekOfMonth(E2)

The full module (copy-paste):

Option Explicit

    Public Const DaysPerWeek            As Long = 7
    Public Const MaxWeekdayCountInMonth As Integer = 5

' Calculates the "weeknumber of the month" for a date.
' The value will be between 1 and 5.
'
' Numbering is similar to the ISO 8601 numbering having Monday
' as the first day of the week and the first week beginning
' with Thursday or later as week number 1.
' Thus, the first day of a month may belong to the last week
' of the previous month, having a week number of 4 or 5.
'
' 2020-09-23. Gustav Brock, Cactus Data ApS, CPH.
'
Public Function WeekOfMonth( _
    ByVal Date1 As Date) _
    As Integer
    
    Dim ThursdayInWeek  As Date
    Dim FirstThursday   As Date
    Dim WeekNumber      As Integer
    
    ThursdayInWeek = DateWeekdayInWeek(Date1, vbThursday)
    FirstThursday = DateWeekdayInMonth(ThursdayInWeek, 1, vbThursday)
    WeekNumber = 1 + DateDiff("ww", FirstThursday, Date1, vbMonday)
    
    WeekOfMonth = WeekNumber
    
End Function


' Calculates the date of DayOfWeek in the week of DateInWeek.
' By default, the returned date is the first day in the week
' as defined by the current Windows settings.
'
' Optionally, parameter DayOfWeek can be specified to return
' any other weekday of the week.
' Further, parameter FirstDayOfWeek can be specified to select
' any other weekday as the first weekday of a week.
'
' Limitation:
' For the first and the last week of the range of Date, some
' combinations of DayOfWeek and FirstDayOfWeek that would result
' in dates outside the range of Date, will raise an overflow error.
'
' 2017-05-03. Gustav Brock, Cactus Data ApS, CPH.
'
Public Function DateWeekdayInWeek( _
    ByVal DateInWeek As Date, _
    Optional ByVal DayOfWeek As VbDayOfWeek = VbDayOfWeek.vbUseSystemDayOfWeek, _
    Optional ByVal FirstDayOfWeek As VbDayOfWeek = VbDayOfWeek.vbUseSystemDayOfWeek) _
    As Date
    
    Dim DayInWeek   As VbDayOfWeek
    Dim OffsetZero  As Integer
    Dim OffsetFind  As Integer
    Dim ResultDate  As Date
    
    ' Find the date of DayOfWeek.
    DayInWeek = Weekday(DateInWeek)
    ' Find the offset of the weekday of DateInWeek from the first day of the week.
    ' Will always be <= 0.
    OffsetZero = (FirstDayOfWeek - DayInWeek - DaysPerWeek) Mod DaysPerWeek
    ' Find the offset of DayOfWeek from the first day of the week.
    ' Will always be >= 0.
    OffsetFind = (DayOfWeek - FirstDayOfWeek + DaysPerWeek) Mod DaysPerWeek
    ' Calculate result date using the sum of the offset parts.
    ResultDate = DateAdd("d", OffsetZero + OffsetFind, DateInWeek)
    
    DateWeekdayInWeek = ResultDate
  
End Function


' Calculates the date of the occurrence of Weekday in the month of DateInMonth.
'
' If Occurrence is 0 or negative, the first occurrence of Weekday in the month is assumed.
' If Occurrence is 5 or larger, the last occurrence of Weekday in the month is assumed.
'
' If Weekday is invalid or not specified, the weekday of DateInMonth is used.
'
' 2019-12-08. Gustav Brock, Cactus Data ApS, CPH.
'
Public Function DateWeekdayInMonth( _
    ByVal DateInMonth As Date, _
    Optional ByVal Occurrence As Integer, _
    Optional ByVal Weekday As VbDayOfWeek = vbUseSystemDayOfWeek) _
    As Date
    
    Dim Offset          As Integer
    Dim Month           As Integer
    Dim Year            As Integer
    Dim ResultDate      As Date
    
    ' Validate Weekday.
    Select Case Weekday
        Case _
            vbMonday, _
            vbTuesday, _
            vbWednesday, _
            vbThursday, _
            vbFriday, _
            vbSaturday, _
            vbSunday
        Case Else
            ' vbUseSystemDayOfWeek, zero, none or invalid value for VbDayOfWeek.
            Weekday = VBA.Weekday(DateInMonth)
    End Select
    
    ' Validate Occurence.
    If Occurrence < 1 Then
        ' Find first occurrence.
        Occurrence = 1
    ElseIf Occurrence > MaxWeekdayCountInMonth Then
        ' Find last occurrence.
        Occurrence = MaxWeekdayCountInMonth
    End If
    
    ' Start date.
    Month = VBA.Month(DateInMonth)
    Year = VBA.Year(DateInMonth)
    ResultDate = DateSerial(Year, Month, 1)
    
    ' Find offset of Weekday from first day of month.
    Offset = DaysPerWeek * (Occurrence - 1) + (Weekday - VBA.Weekday(ResultDate) + DaysPerWeek) Mod DaysPerWeek
    ' Calculate result date.
    ResultDate = DateAdd("d", Offset, ResultDate)
    
    If Occurrence = MaxWeekdayCountInMonth Then
        ' The latest occurrency of Weekday is requested.
        ' Check if there really is a fifth occurrence of Weekday in this month.
        If VBA.Month(ResultDate) <> Month Then
            ' There are only four occurrencies of Weekday in this month.
            ' Return the fourth as the latest.
            ResultDate = DateAdd("d", -DaysPerWeek, ResultDate)
        End If
    End If
    
    DateWeekdayInMonth = ResultDate
  
End Function

Example output - note that weeks are numbered correctly also when crossing New Year:

Answer 2

Edit #1

Based on your comments you can directly use the formula mentioned in the above link to get your result like below:

=ISOWEEKNUM(E2)-ISOWEEKNUM(DATE(YEAR(E2),MONTH(E2),1))+1

Old Answer:

Borrowing the formula provided in the comments ( https://thesmartmethod.com/an-excel-formula-to-get-the-week-of-month/ ), you can use the following formula:

 =IF(AND(WEEKDAY(E2,2)=1, DAY(E2+1)=1),1,ISOWEEKNUM(E2)-ISOWEEKNUM(DATE(YEAR(E2),MONTH(E2),1))+1)

Assuming that your only condition is if first day of week is Monday from previous month and Tue to Sun are in next month