Understanding Amazon Algorithms for New Authors
Understanding Amazon Algorithms for New Authors
Chuck Morgan, Crime Fiction Author
For new authors, Amazon can feel like a vast, mysterious ecosystem where some books rise to the surface effortlessly while others sink without a trace. The truth is far less mystical: Amazon’s algorithms are powerful, logical, and surprisingly predictable once you understand what they’re designed to do. They exist for one purpose — to connect readers with books they’re most likely to buy.
If you’re just stepping into the world of publishing, learning how these systems work is one of the most valuable skills you can develop. It’s not about gaming the system. It’s about aligning your book with the signals Amazon already rewards.
This guide breaks down the core components of Amazon’s algorithms in a clear, accessible way so you can make smarter decisions, avoid common pitfalls, and give your book the best possible chance to succeed.
1. Amazon Is a search engine first, a store second
Most new authors think of Amazon as a bookstore. It behaves much more like Google.
Readers type in:
• “crime thriller with a female detective”
• “Hawaiian mystery series”
• “slow-burn romantic suspense”
• “police procedural box set”
Amazon’s job is to return the most relevant, highest‑converting books for that search.
This means:
• Your keywords,
• Your categories,
• Your title and subtitle,
• Your book description,
• Your Look Inside sample,
• And your sales history
…all work together to tell Amazon who your book is for.
The clearer those signals are, the more confidently Amazon can recommend your book to the right readers.
2. The A9 Algorithm: How Amazon Decides What to Show
Amazon’s primary search algorithm is known as A9. While the exact formula is proprietary, years of testing by publishers and marketers have revealed the core factors it prioritizes.
A9 rewards books that:
• Convert well (people who see the book buy it)
• Maintain consistent sales
• Match reader search intent
• Have strong metadata (keywords, categories, title, subtitle)
• Have a healthy review profile
• Keep readers engaged (for Kindle books)
A9 penalizes books that:
• Have mismatched keywords
• Have low conversion rates
• Have poor or misleading metadata
• Have high return rates
• Have weak or inconsistent sales
In short:
Amazon wants to promote books that make readers happy and make Amazon money.
Your job is to help Amazon understand your book so it can do exactly that.
3. Keywords: The Hidden Engine Behind Discoverability
For new authors, keywords are often misunderstood or underused. Amazon gives you seven keyword fields, and each field can contain long‑tail keyword phrases, not just single words.
A long‑tail keyword is a natural, reader‑style search phrase like:
• “crime thriller set in the American West”
• “female detective police procedural series”
• “Hawaiian noir mystery with a strong female lead”
These phrases do three things:
1. Tell Amazon exactly who your book is for
2. Help you appear in niche, low‑competition searches
3. Unlock hidden categories (like Island Noir or Organized Crime Thrillers)
Amazon’s algorithm reads these phrases and uses them to match your book with readers who type similar searches.
What NOT to do:
• Don’t repeat words from your title or subtitle
• Don’t keyword‑stuff
• Don’t use competitor author names
• Don’t use irrelevant terms just to chase traffic
Amazon is smarter than that, and it will penalize you for it.
4. Categories: Your Book’s First Signal to Amazon
Categories are Amazon’s way of shelving your book. They help readers find you, but they also help Amazon understand your genre.
Most authors choose categories that are:
• Too broad
• Too competitive
• Too disconnected from their actual story
The result?
Your book gets buried.
The smarter approach:
Choose narrow, accurate, low‑competition categories that match your book’s themes, setting, and subgenre.
For example:
• Instead of Mystery, Thriller & Suspense, choose Crime Fiction > Police Procedurals
• Instead of Romance, choose Romantic Suspense > Military Romance
• Instead of Literature & Fiction, choose Noir > Island Noir
The more specific your categories, the easier it is to:
• Rank
• Earn a bestseller tag
• Signal Amazon’s algorithm
• Reach the right readers
5. Conversion Rate: The Algorithm’s Most Important Metric
Amazon tracks every step of a reader’s journey:
• How many people see your book page
• How many click
• How many buy
• How many read (for Kindle)
• How many return
This is your conversion rate, and it’s the single most powerful signal Amazon uses.
If 100 people view your book and 10 buy it, you have a 10% conversion rate.
If 100 people view your book and 1 buys it, you have a 1% conversion rate.
Amazon will promote the 10% book every time.
How to improve your conversion rate:
• A strong, professional cover
• A compelling, scannable description
• A powerful first chapter
• Accurate keywords and categories
• Social proof (reviews, blurbs, endorsements)
Conversion rate is why a great cover and a strong description matter more than almost anything else.
6. The 30‑Day and 90‑Day Windows: Why Launches Matter
Amazon gives new books a temporary boost during:
• The first 30 days
• The first 90 days
During these windows, Amazon is watching:
• How many people buy
• How many pages are read
• How many reviews appear
• How readers respond
If your book performs well early, Amazon will:
• Push it into more search results
• Recommend it in “Customers Also Bought”
• Place it in “Readers Also Enjoyed”
• Show it in email promotions
If your book performs poorly early, Amazon will reduce visibility.
This is why coordinated launches, newsletter swaps, ads, and early reviews matter so much.
7. The “Customers Also Bought” Carousel: Your Book’s Neighborhood
This is one of the most powerful discovery tools on Amazon.
If your book appears next to:
• Similar authors
• Similar genres
• Similar themes
…Amazon will start recommending your book to those authors’ readers.
But if your book appears next to:
• Cookbooks
• Children’s books
• Unrelated genres
…your algorithmic signals get scrambled.
This usually happens when:
• Keywords are inaccurate
• Categories are mismatched
• Friends and family buy your book
• You run ads to the wrong audience
Your goal is to build a clean, accurate “neighborhood” of comparable titles.
8. Reviews: Social Proof and Algorithmic Fuel
Amazon doesn’t reveal exactly how reviews affect ranking, but we know they influence:
• Conversion rate
• Reader trust
• Amazon’s confidence in your book
A book with:
• 20+ reviews
• A 4.3–4.7 average
• Detailed, authentic feedback
…will almost always outperform a book with:
• 2 reviews
• A 5.0 average
• Short, vague comments
Amazon also tracks:
• Review velocity
• Review diversity
• Verified purchases
Slow, steady, organic reviews are ideal.
9. Kindle Unlimited and Page Reads
If your book is in Kindle Unlimited, Amazon tracks:
• Pages read
• Completion rate
• Reader engagement
High engagement tells Amazon: “This book satisfies readers.”
Low engagement tells Amazon: “This book may not be a good recommendation.”
For KU authors, page reads can be just as important as sales.
10. Ads and the Algorithm: A Symbiotic Relationship
Amazon ads don’t directly improve your ranking.
But they do improve:
• Visibility
• Click‑through rate
• Conversion rate
• Sales velocity
And those do improve your ranking.
Ads are essentially a way to feed the algorithm the data it needs to understand your book.
11. The Long Game: Why Consistency Beats Spikes
Amazon rewards:
• Steady sales
• Consistent engagement
• Predictable reader behavior
A book that sells:
• 5 copies a day for 60 days
Will often outperform a book that sells:
• 100 copies in one day
• Then nothing for a week
Slow, steady growth builds a stable algorithmic foundation.
Final Thoughts: Amazon Isn’t Your Enemy, It’s Your Partner
For new authors, Amazon’s algorithms can feel intimidating. But once you understand how they work, they become a powerful ally.
Amazon wants:
• Clear metadata
• Accurate targeting
• Strong reader satisfaction
• Consistent performance
You want:
• Visibility
• Discoverability
• Sales
• Loyal readers
When you align your book with Amazon’s systems, you’re not gaming the algorithm; you’re helping it help you.
If you’re writing crime, thrillers, noir, or police procedurals, genres where you already have deep expertise, these principles become even more powerful. Amazon thrives on clarity, and your minimalist, emotionally resonant approach to storytelling and design fits perfectly with what the algorithm rewards.