When a reader searches for their next book on Amazon, they type a few words into the search bar. If your book doesn't show up, it doesn't exist to that reader. That's the entire game with KDP keywords. Get your book in front of people who are already looking for exactly what you wrote.
Amazon gives you exactly 7 keyword slots when you publish through Kindle Direct Publishing. Seven. That's it. Most authors waste them on single words like "thriller" or "romance," then wonder why their book never appears in search results. This guide covers how to research, choose, and optimize those 7 keywords so your book actually gets found.
What KDP Keywords Are and How Amazon Uses Them
KDP keywords are search terms you enter during the publishing process on Amazon. They live in the backend of your book's listing. Readers never see them directly, but Amazon's search algorithm uses them to decide which books to surface for any given search query.
Think of them as hidden tags. When someone searches "cozy mystery with cats," Amazon scans titles, subtitles, descriptions, category assignments, and keywords to find matches. Your keywords fill in the gaps that your title and description don't cover.
The important part: Amazon treats each keyword slot as a phrase field, not a single-word field. Each slot accepts up to 50 characters. That means you can (and should) enter multi-word phrases, not isolated words. Amazon will match your book to searches that include any combination of words within your keyword phrases.
For example, if one of your keyword slots contains "small town romance second chance," Amazon can match your book to searches for "small town romance," "second chance romance," and "small town second chance", all from a single slot.
The 7-Keyword Limit: How to Get Maximum Coverage
Seven slots, 50 characters each, 350 characters total. That's your entire keyword real estate. The goal is to pack as many relevant, searchable terms into those 350 characters as possible without repeating yourself.
Rules for Maximizing Your Keyword Slots
- Don't repeat words across slots. If slot 1 contains "mystery," don't use "mystery" again in slot 4. Amazon indexes all 7 slots together, so repetition wastes characters.
- Don't repeat words from your title or subtitle. Amazon already indexes those. If your title is "The Midnight Garden: A Gothic Romance," you don't need "gothic" or "romance" in your keywords.
- Use each slot as a phrase, not a single word. "thriller" wastes 43 characters. "psychological thriller unreliable narrator dark" uses 44 characters and covers five different search terms.
- Skip punctuation and filler words. No commas, no "a," "the," or "for." Amazon ignores them anyway. Just string relevant words together separated by spaces.
- Don't use other authors' names or trademarks. Amazon prohibits this and can suppress your listing entirely.
Example: Keyword Optimization for a Cozy Mystery
Say your book is called Murder at the Bakery: A Maple Creek Mystery. Here's what bad vs. good keywords look like:
Bad keywords (wasted slots):
- mystery
- cozy
- murder
- bakery
- detective
- whodunit
- fiction
That's 7 single words. You're competing with millions of books for each one, and "murder" and "bakery" are already in your title.
Good keywords (maximum coverage):
- cozy mystery series female sleuth amateur
- culinary mystery baking chef cooking
- small town whodunit lighthearted funny
- clean wholesome mystery no swearing
- women sleuths cat pet animal lovers
- book club picks page turner quick read
- feel good fiction comfort reads gift
Same 7 slots, but now you're covering dozens of search terms instead of 7.
Keyword Research Methods That Actually Work
You don't need expensive tools to find good KDP keywords. The best research happens directly on Amazon, where readers are actually searching.
Amazon Search Autocomplete
Go to Amazon.com, select "Kindle Store" from the department dropdown, and start typing words related to your book. Amazon will suggest completions based on what real people are searching for right now. These suggestions represent actual demand.
Type your genre, then add a letter at the end. "romance a" gives you "romance alpha male," "romance audiobook," "romance age gap." "romance b" gives you "romance billionaire," "romance book club," "romance beach read." Work through the alphabet and note every suggestion that fits your book.
Competitor Book Analysis
Find 10-15 books similar to yours that are selling well. Look at their titles, subtitles, and descriptions. What words do they use? What categories are they in? The words that keep showing up across successful competitors are the words readers are using to find those books.
Pay attention to the "Customers Also Bought" section on each book's page. This shows you the neighborhood your book will live in, and the language readers in that neighborhood use.
Amazon Category Browsing
Browse through Amazon's Kindle category tree. The subcategory names themselves are keyword ideas. "Kindle Store > Mystery, Thriller & Suspense > Mystery > Cozy > Culinary" tells you that "culinary cozy mystery" is a recognized search path.
Look at the bestseller lists in relevant subcategories. The titles and descriptions of the top 20 books reveal the exact vocabulary your target readers use.
Amazon's "Also Bought" and "Related" Sections
Scroll down on any book listing and look at "Products related to this item" and "Customers who bought this item also bought." These sections reveal how Amazon groups books together. The common threads between these recommended books point directly to the keywords that connect them.
What Makes a Good Keyword
A good KDP keyword hits three marks: specific enough to match reader intent, popular enough to generate searches, and relevant enough to your book that readers who find you will actually buy.
Specific Beats Broad
"Fiction" is a keyword. It's also useless. Millions of books match "fiction." Your book will never rank for it. "Small town women's fiction family drama" is specific. Fewer books compete, and the readers who search for that phrase know exactly what they want.
This is the long-tail principle. The more specific the search term, the fewer results compete, and the higher the chance your book appears on page one. A keyword that gets 50 searches per month but puts your book in position 1 is infinitely more valuable than a keyword that gets 50,000 searches but buries your book on page 40.
Phrase Keywords Over Single Words
Amazon lets you use up to 50 characters per slot. A single word uses 5-10 characters. A phrase uses 40-50 characters and covers multiple search variations. Always think in phrases.
The best keyword phrases combine a genre term, a subgenre or trope, and a descriptor. "Dark fantasy enemies to lovers slow burn" hits genre (dark fantasy), trope (enemies to lovers), and pacing (slow burn) in a single slot.
Reader Language, Not Writer Language
Authors describe their books differently than readers search for them. You might call your book a "literary exploration of grief and identity." Readers search for "sad books that make you cry" or "books about loss and healing." Use the words your readers use, not the words you'd use at a writing conference.
Keywords vs. Categories: They Work Differently
KDP gives you two separate tools for discoverability: keywords and categories. Authors often confuse them or treat them as interchangeable. They aren't.
Categories place your book in Amazon's browsing hierarchy. They determine which bestseller lists your book can appear on and which "top 100" rankings apply to you. You select up to 3 categories during publishing.
Keywords determine whether your book shows up when someone types a search query. They also influence which additional categories Amazon assigns to your book beyond the ones you chose.
Pay attention here: certain keywords can trigger additional category placements. For example, including "short stories" in your keywords might get Amazon to place your book in short story categories even if you didn't select them. Including "new adult" can trigger placement in New Adult categories.
Don't waste keyword slots on your exact category names. You get those through category selection already. Use keywords to target related categories, reader-language search terms, and tropes that category names don't cover.
Common Keyword Mistakes
Most self-published authors make the same keyword mistakes. Avoid these and you're already ahead of much of your competition.
- Using single words. "Romance" as a keyword is like trying to get noticed by shouting in a stadium. Use multi-word phrases that narrow the field.
- Duplicating title words. Amazon already indexes your title and subtitle. Every word you repeat in your keywords is a word you could have used to reach a new search term. If your title contains "thriller," leave "thriller" out of your keywords.
- Being too generic. "Good book" and "bestseller" describe every book. They describe no book. Generic terms attract no targeted traffic.
- Using commas within a slot. Some authors enter "romance, love, dating" in a single slot. Amazon treats the entire 50-character field as one phrase. Commas just waste characters. Enter "romance love dating relationships" instead.
- Copying competitor keywords blindly. A keyword that works for a book with 500 reviews won't necessarily work for your debut. Established books rank for competitive terms because of their sales history. As a newer author, target less competitive long-tail phrases where you can actually rank.
- Setting keywords once and forgetting them. The market shifts. New trends emerge. Seasonal demand changes. Keywords need maintenance.
How to Test and Update Keywords After Publishing
Your first set of keywords is a hypothesis. You're guessing which terms will drive traffic. The only way to know if they work is to measure results and adjust.
Tracking Performance
After publishing, monitor your book's ranking in the categories you're targeting. Check your book's search position for your chosen keyword phrases by searching for them on Amazon and noting where your book appears. If you're not on the first three pages for any of your keywords, those keywords aren't working.
When to Change Keywords
Give a new set of keywords at least 2-4 weeks before changing them. Amazon's algorithm needs time to re-index your book and test it against new search queries. Changing keywords daily accomplishes nothing.
Swap underperforming keywords one or two at a time so you can isolate what's working. If you change all 7 at once and see improvement, you won't know which changes drove the result.
Seasonal and Trend-Based Updates
If your book fits seasonal themes — holiday romance, summer beach reads, back-to-school nonfiction — update your keywords ahead of those seasons. Add "holiday romance Christmas" in October, switch to "beach read summer vacation" in April. Readers search differently depending on the time of year.
Also watch for emerging trends in your genre. If "dark academia" suddenly explodes on BookTok and your book fits, get that keyword in your slots immediately.
Free Tools and Methods for Keyword Research
You don't need to spend money on keyword research tools, especially when you're starting out. The free methods are often more useful because they're based on real Amazon data.
- Amazon Search Bar: The autocomplete suggestions are based on actual search volume. This is the single most valuable free keyword research tool.
- Amazon Bestseller Lists: Browse the top 100 in your target categories. Study titles, subtitles, and descriptions for recurring words and phrases.
- Google Trends: Compare search interest between different keyword variations. "Cozy mystery" vs. "cosy mystery". Google Trends shows you which one readers actually type.
- Goodreads Shelves: See how readers categorize books similar to yours. Shelf names like "dark-romance," "found-family," and "enemies-to-lovers" are literally the words readers use to describe books.
- BookTok and Bookstagram: Social media book communities create and popularize reading terms. Hashtags like #DarkAcademia, #BookishFantasy, and #SlowBurnRomance reflect real reader vocabulary.
- Reddit Book Communities: Subreddits like r/Fantasy, r/RomanceBooks, and r/suggestmeabook are full of recommendation requests that use natural reader language.
How BookSmith Handles Keywords for You
Keyword research is one of those tasks that's straightforward once you understand it but tedious to do well for every book. That's why BookSmith generates optimized Amazon keywords automatically as part of every book project.
When you create a book with BookSmith, the AI analyzes your manuscript content, genre conventions, comparable titles, and current market trends to generate 7 keyword phrases optimized for Amazon search. Each phrase is built to maximize character usage, avoid redundancy with your title, and target the specific search terms readers in your genre actually use.
Your keywords come as part of the publishing metadata package, alongside your book description, category recommendations, and KDP upload checklist. Everything you need to fill out your KDP listing correctly the first time.
Keywords pair well with a strong book description. Our guide on writing a book description that sells on Amazon covers that side. New to KDP entirely? Start with the full guide to self-publishing on Amazon KDP.
Quick Reference: KDP Keyword Checklist
Before you hit publish, run your 7 keywords through this checklist:
- Each slot uses a multi-word phrase (aim for 40-50 characters per slot)
- No words repeated across different keyword slots
- No words duplicated from your title or subtitle
- No commas, quotes, or filler words (a, the, for, etc.)
- No competitor names, author names, or trademarks
- Each phrase combines genre + trope/topic + descriptor
- Keywords reflect reader language, not writer/industry jargon
- At least 2-3 long-tail phrases targeting specific niches
- Phrases cover search terms your title and categories don't
- You have a plan to review and update keywords after 30 days
Your keywords are one piece of a larger discoverability strategy that includes your book description, categories, cover design, and pricing. Get all of them right and your book has a fighting chance in Amazon's search results. Start with BookSmith and let the platform handle the keyword optimization while you focus on your book.