Writing Craft Guide

Amazon Keyword Strategy for Fiction Authors

Amazon keywords are search strings, not single words. Understanding how the A9 algorithm uses them, how to fill your seven keyword slots with phrases that actually convert, and why your ARC readers are doing keyword research for you every time they write a review can move your book from invisible to discoverable without a single ad dollar spent.

Keywords are search strings, not words

Phrases beat single genre terms

Long-tail beats broad

Specific converts; generic competes

ARC reviews are keyword research

Readers tell you how to find more of them

Everything you need to master Amazon keyword strategy

What Amazon Keywords Actually Are

Amazon keywords are not single words; they are search strings. A reader searching for 'enemies to lovers fantasy romance slow burn' is entering a five-word string, and Amazon matches that string against your keyword fields. This means a keyword slot filled with just 'romance' is wasting most of its potential. Every slot allows up to 50 characters, and you should use them for phrases, combinations, and reader-community vocabulary, not individual genre terms. Think of each slot as a sentence fragment that a reader might actually type into the search bar.

How Amazon's A9 Algorithm Uses Keywords

Amazon's A9 algorithm is a purchase-intent engine, not an information-retrieval engine. It does not just match keywords to search terms; it weighs conversion rate, sales velocity, and review count alongside keyword relevance. This means that ranking for a keyword you cannot convert on is actually counterproductive: low click-through and purchase rates on a keyword tell the algorithm your book is not relevant to those searches. Target keywords where your cover, description, and price will convert browsers into buyers. A high-converting narrow keyword beats a low-converting broad one every time.

The Seven Keyword Slots and How to Fill Them

KDP gives you seven keyword slots of up to 50 characters each. Use them for: (1) your primary subgenre combination, (2) key tropes your readers search for, (3) setting or time period, (4) reader-community vocabulary your genre uses, (5) mood or tone terms readers use when describing what they want, (6) comparative terms without violating TOS, and (7) specific reader situations or gift-giving contexts. Do not duplicate terms already in your title or subtitle, as Amazon includes those automatically. Do not use commas; spaces separate terms within a slot.

Long-Tail Keyword Strategy

A long-tail keyword is a specific, multi-word phrase that fewer people search for but that converts at a higher rate because the people who search for it are looking for exactly what you have. 'Fantasy novel' has enormous search volume and enormous competition. 'Standalone dark fantasy romance with female assassin protagonist' has tiny search volume and nearly zero competition, but every reader who types it is looking for your book. Long-tail keywords are the correct strategy for new authors and books below rank 10,000. Broad keywords are only worth targeting when your conversion rate is already strong enough to compete.

Keyword Research: Free Methods

Before spending money on keyword tools, exhaust the free sources. Amazon autocomplete is the most accurate source available because it reflects actual buyer behavior on the platform where your book is sold. Go systematically: type your genre followed by each letter of the alphabet and record the suggestions. Read the reviews of the top twenty books in your category; the language reviewers use to describe what they loved is the language buyers searched to find those books. Browse bestseller lists in adjacent subcategories: terms in book titles and subtitles often signal what readers are searching for.

ARC Reviews as Keyword Research

ARC readers who review your book before launch are performing accidental keyword research. The words they use to describe your book to potential readers are the words those potential readers are likely to search. If three ARC reviewers call your book 'an enemies-to-lovers slow burn with incredible tension,' that phrase belongs in your keywords and your description. Collect and analyze this language before you finalize your keywords. Update your keywords after launch using early review language. The readers who loved your book are telling you, in their own words, exactly how to find more of them.

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Frequently Asked Questions

How many keywords should I use per slot?

Each keyword slot allows up to 50 characters. You are not limited to one keyword per slot; you can enter a phrase, a combination of words, or multiple related terms separated by spaces. Amazon reads each slot as a string and matches it against search queries. This means you can pack more search coverage into a slot by using a phrase like 'paranormal romance werewolf shifter' rather than just 'paranormal romance.' Use every character available in every slot. Unused characters are wasted potential reach. Do not use commas to separate terms; spaces are sufficient and commas count against your character limit.

Should I use my genre as a keyword?

Not as a standalone keyword. Your genre is already reflected in your book categories, which Amazon also uses for search. A keyword slot used for just 'romance' or just 'fantasy' is wasted, because you are competing against every book in that genre for a term that your category already covers. Use keyword slots for more specific terms that your categories do not capture: subgenre combinations, setting-specific terms, trope names, and reader-community vocabulary. Genre terms are most useful when combined with specifics: 'dark fantasy romance enemies to lovers' uses genre as a modifier rather than as the whole term.

Can I use competitor book titles as keywords?

Amazon's terms of service prohibit using other authors' names or specific book titles as keywords. Beyond the policy risk, it is also usually a poor strategy: readers searching for a specific title or author are rarely looking to discover alternatives. They want that book. You are better served by using the descriptive terms that make a book like yours findable by readers who do not yet know your title exists. The exception is when you are writing in a clear subgenre associated with a specific reader community, in which case the community's vocabulary, not its flagship authors, is what belongs in your keywords.

How do I find keywords my readers actually search for?

The most reliable free method is Amazon's own search autocomplete. Start typing a relevant phrase in the Amazon search bar and note what completions appear: these are real searches Amazon users have performed. Work through the alphabet systematically. Type your genre term followed by each letter and record the completions. Also read the reviews of bestselling books in your category; readers describing what they loved about a book use the exact vocabulary they searched for to find it. ARC reader reviews are especially valuable because they are your readers describing your book in their own words.

How often should I update my keywords?

Update your keywords when your book's rank or visibility changes significantly, when a new trend emerges in your genre that your current keywords do not capture, when you notice through ARC reader reviews that readers are describing your book with language not reflected in your keywords, or when Amazon adds or restructures categories that affect your book's browse placement. There is no fixed schedule; keyword maintenance is responsive rather than routine. That said, reviewing your keywords quarterly is a reasonable habit for active authors. Stale keywords on a book that has not sold in six months are worth replacing with fresh terms based on current search behavior.