How Amazon’s Star Rating System Works for Books
Learn about how Amazon’s star rating system works for books when reviews are left on Amazon or Goodreads. It doesn’t take the average!

Learn about how Amazon’s star rating system works for books when reviews are left on Amazon or Goodreads. It doesn’t take the average!
In this week’s blog post, I want to talk about how Amazon’s rating system works when you leave star ratings and reviews for books that you read.
You would think that if a book had a five-star rating and a one-star rating, they would average out to be three stars…. but they don’t.
About six weeks ago, I published my book “A Dear, Sweet Girl,” and I had the epilogue be the freebie for signing up for my newsletter. As you may have seen, it didn’t go well. Sure, I may have gotten 300x the number of signups that I usually do, but it also made a LOT of people angry, and they expressed that anger by leaving 1-star reviews on Amazon.
Now, I’ve had my fair share of bad reviews from my books. Someone doesn’t like the JAFF trope I wrote, or they found more typos than they’d like. But I don’t really read negative reviews anymore, because all they do is make me want to curl into a ball and cry, and quit writing altogether.
But the one thing that stood out the most from all these one-star reviews (other than I should never leave out the epilogue again, lol) was that the math didn’t make sense.
Now, I got my degree in math. I was a middle school math teacher for several years before developing Crohn’s, having kids, and staying home to homeschool them and take care of my health. I love numbers, probably more than I love reading, and with just a few ratings and most of them being so low (which hadn’t happened before), I quickly could see that the average didn’t work out.
So it caused me to do a deep-dive into how Amazon calculates star ratings. It’s NOT just the average, believe it or not.
There’s actually two different types of ratings: those that are just a star, and those that have a star and a typed review. Ratings that have a review attached are weighted more heavily. Additionally, if you are a “verified purchaser” of the book (meaning Amazon sees that you actually purchased or borrowed the book), then your star has more value as well.
According to Amazon’s website, here’s how those ratings are calculated:
Amazon calculates a product’s star rating using machine-learned models instead of a simple average.
These models consider factors such as how recent the rating or review is and verified purchase status. They use multiple criteria that establish the authenticity of the feedback. The system continues to learn and improve over time.
We do not consider customer ratings without an Amazon Verified Purchase status in a product’s overall star rating until a customer adds more details in the form of text, image, or video.
If you want to read more in-depth about how Amazon’s ratings and reviews work, check out this article here.
I bring this all up just to let everyone know that your ratings and reviews DO matter. It takes a lot more to recover from poor reviews, and a 4-star review may not be worth what you think it is.