This function returns the number of bytes used on the directory:

 Function DirUsedBytes(ByVal dirName As _        String) As LongDim FileName As StringDim FileSize As Currency' add a backslash if not thereIf Right$(dirName, 1) <> "" Then        dirName = dirName & "" EndifFileSize = 0FileName = Dir$(dirName & "*.*")Do While FileName <> ""        FileSize = FileSize + _                FileLen(dirName & FileName)        FileName = Dir$LoopDirUsedBytes = FileSizeEnd Function

You can call the function passing the name of a directory:

 MsgBox DirUsedBytes("C:Windows")