This shows how to display the size of a directory on your hard disk , this example uses a fictitous folder , change to one of your own folders.

<%
Dim objFSO , objFolder
Set objFSO = Server.CreateObject("Scripting.FileSystemObject")
Set objFolder = objFSO.GetFolder("d:\asp")
Response.Write "The folder is " & objFolder.Size & "bytes"
%>

If you wanted to display the size of a directory on your server you could use this.

<%
Dim objFSO , objFolder , PathToFile
Set objFSO = Server.CreateObject("Scripting.FileSystemObject")
PathToFile = Server.MapPath("/yourdirectory")
Set objFolder = objFSO.GetFolder(PathToFile)
Response.Write "The folder is " & objFolder.Size & "bytes"
%>