[nsp] Memory required for a given number of routes

[rwcrowe at comcast.net]

Hello,
      This tool/procedure might be available somewhere, so just bear with me. I am looking for a way for pre- implementation to calculate the requires memory for a given number of routes. Say a customer needs to have 45,000 routes in their routing table, what would be the minimum memory required for just the routes ? Obviously you need extra memory for routing functions and processes.
    It doesnt have to be an exact amount but just a round about figure. Also if it could be generic enough so you dont have to specify BGP, OSPF, etc as they do take differnt memory requirements.
 If the router is already implemented you could do a "show ip route summary" but I am looking for this as a pre-sales/pre-implementation method. 
Thanks
Rob