Определить размер папки на компьютере в байтах

    Function GetSize(ByVal d As DirectoryInfo) As Long
        Dim Size As Long = 0
        Dim fis As FileInfo() = D.GetFiles()
        For Each fi As FileInfo In fis
            Size += fi.Length
        Next
        Dim dis As DirectoryInfo() = D.GetDirectories()
        For Each di As DirectoryInfo In dis
            Size += GetSize(di)
        Next
        Return Size
    End Function
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim D As DirectoryInfo = New DirectoryInfo("D:\Game`s")
        MsgBox(GetSize(D))
    End Sub

    Function FolderSize(ByVal Path As String) As Long
        Dim FolSize As Long = 0
        For Each File As String In IO.Directory.GetFiles(Path, "*", IO.SearchOption.AllDirectories)
            FolSize += New IO.FileInfo(File).Length
        Next
        Return FolSize
    End Function