Ever since July 2015 Amazon has been paying authors and publishers with works in Kindle Unlimited by the page, and on 1 February 2016 Amazon adjusted how it calculated the page size.
Amazon quietly announced on the KDP support forums on Monday that it had developed a new algorithm for calculating the Kindle Edition Normalized Page Count, or KENPC.
The retailer said that the new method, which has been dubbed KENPC v2.0, "makes a number of improvements to how we standardize font, line height, and spacing used to normalize the length of each book relative to one another. This change will impact the KENPC of some titles while others will remain unchanged. The average KENPC will change less than 5%, although individual books’ changes may be larger or smaller. The new KENPC approach will be applied uniformly to all KDP Select books and all versions of those books."
In related news, Amazon has also added a cap on the maximum number of pages an author can earn from a single reader in a single title (3,000 Kindle Edition Normalized Pages).
Amazon says that only the very longest books will be affected, and given that authors have reported that, say, a 300 page paperback has a KENPC of around 500 to 600 and that a box set ran to around 2,000, I would bet Amazon is correct in that regard.
However, early reports suggest that the new KENPC v2.0 algorithm will not have a similar mild impact. Several authors are reporting a sharp decline. One said that "I had one of my 15 books drop 12.5% in KENP".
Another reported "Mine dropped by exactly 13% which would amount to about 26 cents per book based on a half cent per page payout. The format and fonts are pretty normal and everything is straight text with no gaps."
And a third said that "I went over all my books and didn't find any significant changes - maybe a dozen pages here or there, out of 300-600. So no problems here."
So clearly results are mixed.