5000 terabytes is 5,120,000 gigabytes. At $0.037 a gigabyte a month, Dropbox would have a bill of $189,440 a month. At $9.99 a month for 100 gigabytes of data, Dropbox needs 18,963 paying customers to meet that bill. 18,963 times 100 gigabytes is 1,896,296, which leaves 3,223,704 gigabytes of space Dropbox can dole out to its non-paying users. That's not 96 per cent of the capacity it pays for, but given Dropbox's customers at all levels probably don't use all their capacity it's not hard to see how Dropbox could get mighty close to a profit even if it pays AWS' published price, which we can't imagine it does.
So is Amazon making a profit on Cloud Drive's paid plans? AWS' genesis as Amazon's private cloud means it is sensible to assume Cloud Drive runs on S3 or something an awful lot like it, charged back between business units at low, low, mi casa es su casa prices. That could mean AWS can operate cloud storage space rather more cheaply than its advertised rates and almost certainly more cheaply than it charges even colossal customers like Dropbox.Go read the whole piece.