How do I find the last column with data?

Here's something which might be useful. Selecting the entire column based on a row containing data, in this case i am using 5th row:

Dim lColumn As Long

lColumn = ActiveSheet.Cells(5, Columns.Count).End(xlToLeft).Column
MsgBox ("The last used column is: " & lColumn)

I have been using @Reafidy method/answer for a long time, but today I ran into an issue with the top row being merged cell from A1-->N1 and my function returning the "Last Column" as 1 not 14.

Here is my modified function now account for possibly merged cells:

Public Function Get_lRow(WS As Worksheet) As Integer
 On Error Resume Next
 If Not IsWorksheetEmpty(WS) Then
  Get_lRow = WS.Cells.Find("*", SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
  Dim Cell As Range
  For Each Cell In WS.UsedRange
   If Cell.MergeCells Then
    With Cell.MergeArea
     If .Cells(.Cells.Count).Row > Get_lRow Then Get_lRow = .Cells(.Cells.Count).Row
    End With
   End If
  Next Cell
 Else
  Get_lRow = 1
 End If
End Function

Public Function Get_lCol(WS As Worksheet) As Integer
 On Error Resume Next
 If Not IsWorksheetEmpty(WS) Then
  Get_lCol = WS.Cells.Find(What:="*", after:=[A1], SearchOrder:=xlByColumns, SearchDirection:=xlPrevious).Column
  Dim Cell As Range
  For Each Cell In WS.UsedRange
   If Cell.MergeCells Then
    With Cell.MergeArea
     If .Cells(.Cells.Count).Column > Get_lCol Then Get_lCol = .Cells(.Cells.Count).Column
    End With
   End If
  Next Cell
 Else
  Get_lCol = 1
 End If
End Function

Here's a simple option if your data starts in the first row.

MsgBox "Last Row: " + CStr(Application.WorksheetFunction.CountA(ActiveSheet.Cells(1).EntireRow))

It just uses CountA to count the number of columns with data in the entire row.

This has all sorts of scenarios where it won't work, such as if you have multiple tables sharing the top row, but for a few quick & easy things it works perfect.