Social network website in php

I`m aboutto lunch my website,a socialnetwork website.
I never did project like this before,so i was wondering if anyone can explain to me How much space of the server will i need.
Because for people photos they will be uploading to the server,then thelink to the database.
So i dont know how much space i`m i gonna need.

 

It really all depends on howmany users you will get, and howbig the files (photo's) you are allowing to be uploaded.

 

lets imagine i have 100,000 members and i allow up to max 20mb photo upload.
and each member can upload profile photo and create albums.
for begining how much space i`m i going to need??

 

In that case.

100000 users x 20MB = 2000000 megabytes > 1953.125 gigabytes > 1.90734863 terabytes
So lets say 2 terabytes as not all users will upload 20MB.
Add a little bit extra (just in case) for OS and website code.

 

This is alot,And how is this going to cost me?
If there are cheaper hosts please direct me))))

 

Cheaper than what?

 

i mean Cheaper HOSTS.
Where i will be able to pay for those 2terabytes for my website.