5,000 downloads are needed to displace a single CD sale (assumed song downloads)
at 12 songs a CD
5,000/12 = 417 album downloads to replace 1 CD sale
CD =18$
total dl's to date = 34,277,829 (this includes non-music downloads, so this number is higher than the actual number of music downloads)
29 months since the founding of What.CD (October 2007-May 2010)
Current amt of users: 122,824

5000/12 = 416.6666
~417 album downloads per CD

Downloads/displaced cds
417/1=34,277,829/x
x= 82,201.0288 → amount of album sales displaced by What.CD use to date

82,201.0288*18 = 1,479,618.52 → total cost of all What.CD music (and other stuff, remember, so this figure is higher than a pure music number) transferred

1,479,618.52/29 = 51,021.3283 → total $ amount transferred every month

51,021.3283/122,824 = 0.415401943 → total $ amount each user displaces every month from the music industry

Yes, that's less than 42¢. Think about that next time you're at 711.

And that estimate is (probably) high.

*notes: for 5k downloads per album, see

Bender, M. , & Wang, Y. (2009). The Impact of Digital Piracy on Music Sales: A Cross-country Analysis. International Social Science Review, 84(3/4), 157-170.

which cites

Oberholzer-Gee, F. , & Strumpf, K. (2007). The Effect of File Sharing on Record Sales: An Empirical Analysis.Journal of Political Economy V. 115 No. 1 (February 2007) P. 1-42, 115(1), 1-42.

for that statistic

12 songs/album I just figured reasonable.
18$ an album I just figured was the cost of a new CD these days.
All other stats grabbed from the What.CD home page.

Downloaded total includes stuff other than music, so that isn't exactly accurate. Not sure where I'd get an accurate number for that. If someone wants to either a) tell me where/whom to ask or b) just do it and plug it in and get a new total, that would be appreciated.