Kindle Unlimited: Amazon's Ebook Subscription and the Pages-Read Royalty Model

Kindle Unlimited (KU) is Amazon's ebook subscription service, launched in July 2014 at $9.99 per month with an initial catalog of over 600,000 titles plus thousands of audiobooks. Subscribers can borrow and read an unlimited number of enrolled titles for the flat monthly fee. Authors and small publishers make their books available in KU by enrolling in KDP Select, the exclusive arm of Kindle Direct Publishing. Major trade publishers (such as Houghton Mifflin Harcourt, Simon & Schuster, and Workman) have also placed titles in KU under separate arrangements. Compensation model: Amazon initially paid a flat per-borrow fee once a reader passed 10 percent of a book. In July 2015 it switched to a pages-read model based on Kindle Edition Normalized Pages (KENP), which standardizes page counts across formats. Authors are paid from a monthly KDP Select Global Fund divided across total pages read, so the effective per-page rate fluctuates month to month (often around half a cent per page). Annual payouts to authors have run into the hundreds of millions of dollars (roughly $200 million in 2016, over $300 million by 2019). The pages-read model favors longer works and incentivizes serialized, fast-released fiction, and the exclusivity requirement is the source of practices like Web Fiction \"Stubbing\": How Serial Authors Comply With KDP Select Exclusivity. See KDP Select Exclusivity: What Enrolling Locks You Out Of.