Amazon Kindle is nothing but a bookstore. Every book needs to be on a ‘shelf’, which is called ‘category’ there, and has a set of ‘tags’, which are the ‘keywords’. The categories tell the store where to file a book, and the keywords are the terms readers type when they’re looking for something.

Selling books on Amazon comes down to visibility. By 2025, ranking depends on two key factors: relevance (whether your book is placed in the correct category) and conversion – do readers click, sample, and read when they see it? If those two factors are met, the algorithm will learn which people are most likely to purchase your book and attempt to sell to more of them.

The challenge is alignment. Your metadata has to match the promise your book actually makes. An imprecise Amazon book category makes your book invisible to your target readers, and Amazon doesn’t reward vague keyword stuffing.

Define the Promise Before You Choose Anything

Every category decision begins with clarity on what your book is promising. Begin by identifying your book’s core genre and subgenre, then research similar top-selling books to see which categories they use. Choose categories that precisely match your book’s content and audience by drilling down to the most specific subcategories available.

Take The Martian. The hook is survival on Mars through problem‑solving and real‑world science. That’s why it belongs to Science Fiction & Fantasy > Science Fiction > Hard Science Fiction and Science Fiction Adventure. Matching keywords like ‘Mars survival’ and ‘astronaut stranded’ put it in front of the readers most likely to connect with it.

Legends & Lattes found success by ranking in specific Amazon categories: Fantasy, Romance, and LGBT+. Shelving in these focused subcategories connects the book directly with readers searching for queer fantasy stories centered around romance, community, and low-stakes magic. This precise category placement – and keywords like ‘low stakes fantasy’ and ‘coffee shop fantasy’ – were crucial to its breakout, making sure the right audience found the story about an orc’s fresh start and her charming new coffee shop.

Tone and Mood Are Also Category Clues

Categories aren’t just about genre mechanics; they also map to tone.  The Cat Who Could Read Backwards is classic ‘cozy mystery’, placed in a subcategory (Mystery, Thriller & Suspense > Mystery > Cozy > Animals) where readers expect gentle pacing, quirky amateur sleuths, and minimal violence. It serves readers looking for comforting, entertaining mysteries without graphic content or dark themes.

On the other side of the spectrum, Prince of Thorns thrives in Amazon’s Dark Fantasy subcategory. This shelf is reserved for stories defined by a bleak, intense, and morally complex tone – full of violence, antiheroes, and a grim atmosphere. By placing Prince of Thorns in Dark Fantasy, the book connects directly with readers seeking ruthless characters and a world where hope is scarce. Here, tone is not an afterthought; it’s the defining feature of the subcategory, signaling to the audience exactly the emotional and thematic experience they’ll get.

Tone is metadata. Ignore it, and you risk shelving your book among titles that repel your actual audience.

A Workflow for Choosing Amazon Categories and Keywords

This is where process prevents guesswork. A consistent workflow helps you choose strategically instead of emotionally:

• Define the promise. Identify two core themes or tropes, plus tone.
• Study comparable titles (comps) to yours. Find five to ten successful books aimed at your same reader and analyze their category chains.
• Select strategic shelves. Start by picking the most specific category that fits your book. As you gain experience and data, you can experiment with broader categories to increase your audience.
• Craft seven keyword phrases. Cover trope, setting or time period, role/archetype, tone, subgenre, and an audience signal.
• After selecting your keyword phrases, search for each one in the Kindle Store. If the results show mostly similar books (same genre or audience), you’ve chosen a good keyword. If you find unrelated books, try different keywords until you see titles that align with what your ideal readers would enjoy.

 These steps make your book easier for the right readers to find, help you avoid common beginner mistakes, and increase your chances of real, sustained visibility and sales in the Kindle Store.

Guardrails That Keep Metadata Working

Amazon’s algorithm is unforgiving if your metadata attracts the wrong clicks. To avoid slipping into obscurity:

• Don’t repeat category terms or your book title in keyword slots. Use them for nuance the category tree can’t express.
• Don’t stuff irrelevant hype or brand names. It dilutes trust and may trigger suppression.
• Don’t pick categories that don’t match your book’s true genre or content just to reach an easy #1 spot. Irrelevant traffic damages conversion rates.
• Review choices every few weeks. If page views are high but page reads are low, your targeting is off.

Practical Takeaway

Categories and keywords on Amazon are your primary sales scaffolding. Categories put your book in the right digital aisle. Keywords explain to actual humans what kind of experience they’ll get if they walk down it.

Authors who thrive aren’t hacking the algorithm. They’re guiding it honestly, shelving their books where the right readers browse, and speaking in the same phrases those readers actually use.

When you treat categories and keywords as precision tools instead of afterthoughts, you stop fighting with SEO and start letting it work for you.

Beyond SEO: What Really Powers Book Sales

Selecting the right categories and crafting strong metadata are vital steps for giving your book a chance at success. Still, good metadata alone won’t guarantee visibility or sales – the real drivers are sales velocity, conversion rate (how many browsers actually buy your book), and consistent page reads for Kindle Unlimited titles.

To achieve that, it is crucial to launch with strong initial sales, promote genuine reader engagement to convert visitors into buyers, and drive external traffic to Amazon through ads, social media, or newsletters.

Advertising spend and external traffic give your book momentum, but targeted metadata helps you connect with readers who are genuinely interested, keeping your rankings strong and your sales sustainable. Fine-tune your categories and keywords, and watch how much farther your marketing efforts can go.

Further Learning: Extra Resources For Book Marketing

If you want to expand your marketing toolkit, these books provide actionable advice to help you reach more readers.

• The Author’s Guide to Marketing Books on Amazon by Rob Eagar is a practical guide focused on strategies to boost book sales specifically within the Amazon ecosystem. It covers category selection, keyword strategies, and advertising tactics that authors need to understand to grow their visibility.

• How to Market a Book: Overperform in a Crowded Market by Ricardo Fayet is a well-regarded, practical guide for authors, and it dedicates a meaningful section to Amazon marketing, including advice on metadata (titles, keywords), book descriptions, and how Amazon’s recommendation algorithms work to help readers discover your book. It also covers paid advertising, review strategies, and the importance of sales momentum for visibility in the Kindle Store.

• Book Marketing from A to Z by Francine Silverman. The book is a compilation of tips, anecdotes, and strategies contributed by over 300 authors, marketing professionals, and publicists, covering every aspect of book marketing – social media, signings, reviews, ads, pre-launch, and so on.