It takes over 45,000 plays on Spotify to generate the same revenue as one album sale

"Consider Pandora and Spotify, the streaming music services that are becoming ever more integrated into our daily listening habits. 

My BMI royalty check arrived recently, reporting songwriting earnings from the first quarter of 2012, and I was glad to see that our music is being listened to via these services. Galaxie 500's "Tugboat", for example, was played 7,800 times on Pandora that quarter, for which its three songwriters were paid a collective total of 21 cents, or seven cents each. Spotify pays better: For the 5,960 times "Tugboat" was played there, Galaxie 500's songwriters went collectively into triple digits: $1.05 (35 cents each).

To put this into perspective: Since we own our own recordings, by my calculation it would take songwriting royalties for roughly 312,000 plays on Pandora to earn us the profit of one-- one-- LP sale. (On Spotify, one LP is equivalent to 47,680 plays.)"

Source:  Damon Krukowski of Galaxie 500 and Damon & Naomi writing on Pitchfork, 14th November 2013