New Feature: Category Data on Kindle Unlimited and Large Publishers (Plus Stats!)

Here at Publisher Rocket, we’re always investigating ways authors can use data to improve online sales. That’s why we just released a new feature showing the percentage of Kindle Unlimited and Large Publisher titles in each Amazon category! 

Both of these metrics are critical to understanding your target audience and competitors, so you can make informed decisions about your book’s placement on the Amazon store.

showing the category data for various kindle unlimited and traditional publishers


  1. To calculate the percent Kindle Unlimited, we analyzed the top selling books in that category and marked if they were enrolled in KU or not.
  2. To calculate the percent of books published by a large publisher, we analyzed the top selling books in that category and marked if they were published by a large publisher that has made major sales, and have published multiple authors in that genre or area.
  3. Please note that just because a book is in KU, doesn't necessarily mean that it wasn't backed by a large publisher or vice versa. Furthermore, there are many books that aren't in KU and are not backed by large publishers.  

Key Stats and Data Findings

Because of this new system, we have been analyzing across the board a LARGE AMOUNT of data from Amazon and will continue to do so over the next couple of months. So far though, here are some interesting tid-bits that we found will looking at the data:

  • When a KU book is downloaded (doesn't include being read), this is equal to Amazon as if it was bought, and affects the Amazon Bestseller Rank just the same.
  • Books listed in the Top 1000 in Amazon's total ABSR that were enrolled in KU were significantly boosted by KU downloads over that of sales in a mass majority of the time.
  • Audiobooks tend to be dominated by big publishers, likely due to high costs to enter the market as well as more offers by these publishers to independent authors. On average, audiobook categories tend to be 85% Large Publisher titles.
  • Romance and Humor & Entertainment led the charge for Kindle Unlimited heavy parent categories, each with around 80% of their top performers in KU.
  • Categories with the highest amount of Large Publisher titles tended to have the least amount of Kindle Unlimited titles. For every 10% of additional titles in Kindle Unlimited, the percentage of Large Publishers fell by 4% on average.
  • For Kindle, the best ranking categories tend to be around 70% Kindle Unlimited and 20-30% Large Publisher. However, the difference in performance is minor.
  • The best ranking book categories are still dominated by publisher heavy genres, with categories at 60-90% Large Publisher titles performing the strongest.
  • Factual and branded content tend to have higher Large Publisher percentages. Sometimes, categories break the mold, such as test preparation books or books on studying foreign languages.
  • There are cases where a single series can skew category information- for example, if there are 15 books in a well read series dominating a small category, the category data will reflect that series’ attributes.

So What’s Next?

At Publisher Rocket, we’ve just started our quest to dive into the data and better understand ways authors can use it to their advantage. Our computer fans are whirring at full speed, struggling to keep up as we sift through piles of numbers.

Additional interesting trends are coming soon – so stay tuned for more useful data at your fingertips.

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