Function GetFolderSize(ByVal DirPath As String, _
   Optional IncludeSubFolders as Boolean = True) As Long
 
  Dim lngDirSize As Long
  Dim objFileInfo As FileInfo
  Dim objDir As DirectoryInfo = New DirectoryInfo(DirPath)
  Dim objSubFolder As DirectoryInfo
 
Try
 
'Länge dazufügen
  For Each objFileInfo In objDir.GetFiles()
    lngDirSize += objFileInfo.Length
  Next
 
'Überprüfen ob die Unterordner auch mit einbezogen werden sollen
If IncludeSubFolders then
  For Each objSubFolder In objDir.GetDirectories()
    lngDirSize += GetFolderSize(objSubFolder.FullName)
  Next
End if
 
Catch Ex As Exception
 
 
End Try
 
   Return lngDirSize
End Function