I didn't know the answer until you asked. So far this site is tiny, only around 50MB of disk space other than the database. Another forum I host on the same server has, with ancillary stuff, around 3.3GB after 7 years. Since that server has 158GB of free space on the drive I'm not exactly worried about it!
These days with hosting the issue is bandwidth, not server space. All of the sites I host, including my business, use an average of 200Kbps during business hours and 100Kbps at night, on a 1536Kbps T-1 line. So again, nothing to worry about.