How much Server capacity needed for each hundred, or thousand members??

average 8Mb per user

yes me too i want to know... for make the server hosting i choose enough stable...

if its shared hosting, then CPU usage would be limited, and maybe as many as 64 other sites sharing the same CPU.
8mb would be a guess, its haed to predict who posts what and how much, with images it can go up fast,

Especially if you ahve video uploads enabled, that will use more diskspace and badwidth. Bandwidth is measured for anything upload and downloaded..

We understand that...just asking for actual useage from those operating sites. Do you have an operational site jchase003e?? Would you do me a favor??? Just take your actual monthly usage for each of the 4 categories listed in my question. and divide by your actual total members. We are all looking forward to those figures. Thank you.

I guess you first need to have a dedicated server for optimized CPU and site performance, and provide for at least 20 Mb of space for each user in my opinion. Videos take a lot of space. Or you may want to provide for 5 to 8 Mb per user but limit each memeber's upload file sizes. If you operate a large member hit rate site with shared hosting, members may fall asleep before their page loads. No member stays more than 30 seconds for a page to load before he is gone.

Im guessing a
QUAD 4 SERVER ( dedicated server )
100 gb of hard drive space ( sata of course )
1gb of Ram at least or more
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thats probally a EXCELLENT START !