Amazon has only disclosed that this 2 year old service now has a catalog of 475,000 titles, but they have yet to tell us how many of their customers are making use of it. This is intensely frustrating to any numbers geek, but if we look elsewhere for the data we can get a good idea of the minimum number of users.
Earlier this week Amazon released their annual back-patting press release. There weren't any details on the number of Kindle tablets or ebook readers sold, nor did Amazon say anything about how many ebooks they sold. Amazon did tell release details about the additional 200,000 exclusive titles in the Kindle Store, and that only 150 indie authors sold more than 100,000 copies of their ebooks via KDP (100k is not a huge number for an author with a decent sized backlist).
And most importantly for this post, Amazon told us that the Kindle Owner's Lending Library stocked "more than 475,000" titles. That is up considerably from the "over 250,000" titles which Amazon claimed last year. Yes, the catalog nearly doubled in size, though it's not clear where the titles came from.
If I had to guess I would say that some of the titles are from indie authors who signed up with KDP Select. Some were interested in the promotional value, but others were interested in pursuing the 70% payment option for the Kindle Stores in India, Brazil, Japan, and Mexico. In order to get the higher payment option in those specific markets, Amazon requires that a title also be in KDP Select (the feeder program for Kindle Owner's Lending Library). Any title in that program must be exclusive to the Kindle Store.
I'm not so sure that those markets are important enough to attract 200,000 new exclusive titles, not when most of western Europe (as well as NZ and AUS) is included in the 70% option with no exclusivity requirement, but I could be wrong.
So now that we know that KOLL has a catalog of "more than 475,000" titles, would anyone care to guess how many of Amazon's customers are actively using it?
My guess is that there's at least a million readers participating every month, but all I can say for certain is that there are at least 447,000 active users.
I got that number by looking at Amazon's publicly disclosed funding for KDP Select. KDP Select has been averaging about 400 thousand to 500 thousand loans each month for all of 2013 (aside from January, which hit 760,000 loans). In November the created a pool of $1.1 million to pay to participating authors, and averaged $2.46 per loan with about 447,154 loans made.
Credit goes to Morris Rosenthal of Foner Books for tracking the payment and funding every month.
This of course doesn't present a complete picture of how many readers participate in Kindle Owner's Lending Library; it is almost certainly low (I think it misses about half). But it does give us a minimum threshold for participants. It also tells us that KOLL is almost certainly one of the top 3 ebook subscription services.
The only one that I think could have more customers is Scribd, which launched their service in early October, taking it international on day one. But since neither Amazon nor Scribd has shared any hard data your guess is as good as mine which is more successful.
Would anyone care to make a guess?