How to Find Keywords for KDP Books

You find keywords for KDP by researching what real readers type into Amazon's search bar, then selecting 7 backend keywords that balance search volume with low enough competition to actually rank. The process combines Amazon's autocomplete suggestions, competitor analysis, and dedicated keyword tools. Get this right and your book shows up where buyers are already looking. Get it wrong and you're invisible.

Why KDP Keywords Matter More Than You Think

Amazon gives you 7 keyword slots in your KDP dashboard. Each slot can hold a short phrase (up to 50 characters). These backend keywords tell Amazon's algorithm what your book is about and which searches should surface it.

Here's what most new authors miss: your keywords don't just affect search rankings. They influence which "also bought" carousels you appear in, which category pages your book lands on, and even which ads Amazon lets you run. A book with lazy keywords like "romance" or "thriller" competes against millions of titles. A book with specific, well-researched phrases like "small town second chance romance" competes against thousands. That's a very different game.

Start With Amazon's Search Bar

The simplest method is free and takes about 20 minutes. Go to Amazon, make sure you're in the Kindle Store, and start typing phrases related to your book's topic or genre.

Amazon autocomplete will suggest completions based on what real shoppers search for. Type "cozy mystery" and you might see "cozy mystery with cats," "cozy mystery series for women," "cozy mystery books 2024." Each of those is a real search term with real demand behind it.

Do this systematically:

Type your main genre or topic, note every suggestion
Add a letter after it ("cozy mystery a", "cozy mystery b") and record what appears
Try synonyms and related angles ("cat mystery," "funny mystery")
Check what phrases appear in the titles and subtitles of top-selling competitors

You'll end up with a raw list of 30 to 80 phrases. That's your starting pool.

Analyze Your Competitors' Keywords

Pull up the top 10 to 20 books in your niche. Look at their titles, subtitles, descriptions, and review language. Pay attention to the exact words readers use in reviews because those phrases often match search behavior.

If you see "enemies to lovers workplace romance" repeated across multiple bestseller subtitles, that tells you two things: readers search for it, and it converts. Write those phrases down.

Also check the categories those books are listed in. Sometimes the category path itself reveals keyword ideas. A book filed under Kindle Store > Mystery > Women Sleuths > Cozy gives you "women sleuths" and "cozy" as potential keyword components you might not have considered.

Use a Keyword Research Tool Built for KDP

Manual research gives you ideas. Tools give you data. You need both.

A good KDP keyword tool shows you estimated search volume, competition scores, and sometimes the number of competing titles for a given phrase. This is where you separate the keywords worth using from the ones that just sound good.

PublishRank's Keyword Research Tool is built specifically for this. You enter a seed keyword, and it returns related phrases with the metrics that actually matter for KDP authors: how many people search for it on Amazon and how many books already target it. That ratio of demand to competition is everything.

Whatever tool you use, the goal is the same: find keywords where the search volume is decent (people actually type this) and the competition is manageable (you have a realistic shot at page one).

How to Choose Your Final 7 Keywords

You've got your big list. Now you need to pick 7. Here's how to filter:

Relevance first. If a keyword doesn't accurately describe your book, drop it. Irrelevant keywords might get impressions, but they won't get sales. Worse, they'll hurt your conversion rate, and Amazon tracks that.
Don't repeat words already in your title or subtitle. Amazon indexes those automatically. If your title says "Cozy Mystery," you don't need "cozy mystery" as a backend keyword. Use that slot for something different.
Mix broad and specific. One or two broader terms for volume, four or five longer phrases for precision. "Small town mystery with female detective over 50" might only get 200 searches a month, but the people searching that phrase know exactly what they want and they're ready to buy.
Skip punctuation and filler words. Amazon ignores "a," "the," "for," and similar words. Don't waste character space on them.
No competitor names or trademarked terms. Amazon can suppress your book for this. Not worth the risk.

Revisit Your Keywords Regularly

Keyword research isn't a one-time event. Reader search behavior shifts with trends, seasons, and cultural moments. A keyword that was gold six months ago might be oversaturated now. A new subgenre term might be emerging with almost zero competition.

Check your keywords every 60 to 90 days. Look at your book's sales rank and traffic. If it's stagnating, swap out your weakest performing keywords and test new ones. KDP lets you update backend keywords anytime without affecting your reviews or ranking history.

One practical tip: keep a spreadsheet of every keyword you've tested, when you used it, and what happened to your sales during that period. Over time, you'll build a personal database of what works in your specific niche. That's worth more than any generic advice.

Frequently Asked Questions

How many keywords can you add to a KDP book?

Amazon gives you 7 keyword boxes, each with a 50-character limit. You can enter single words or short phrases. Use all 7 slots. Leaving any blank is leaving discoverability on the table. You don't need commas or separators within a single box, just type the phrase naturally.

Can you change KDP keywords after publishing?

Yes. Log into your KDP dashboard, go to your bookshelf, click the ellipsis menu next to your book, and select "Edit book details." Scroll down to the keyword fields, make your changes, and hit publish. Updates usually go live within 24 to 72 hours. There's no penalty for changing keywords, and your existing reviews and ratings stay intact.

Should I put keywords in my book title on KDP?

For nonfiction, almost always yes. A title like "Keto Meal Prep: Easy Low-Carb Recipes for Beginners" packs in searchable terms naturally. For fiction, it depends on the genre. Many fiction authors use subtitles or series taglines to include keyword-rich phrases without making the main title feel stuffed. The key is to make it read naturally to a human while still giving Amazon's algorithm something to index.

What's the difference between KDP keywords and categories?

Keywords are the 7 backend phrases you enter during publishing. Categories are the browse sections (like "Science Fiction > Space Opera") where your book gets shelved. They work together but serve different purposes. Keywords affect search results. Categories affect browse visibility and bestseller list eligibility. You can use specific keywords to trigger additional category placements that aren't available in the standard category selector.

Are free KDP keyword tools accurate enough?

Free tools like Amazon's autocomplete and manual competitor research are a solid starting point. They tell you what phrases exist and that people use them. What they don't tell you is volume or competition numbers. For casual publishers with one or two books, free methods can work fine. If you're building a catalog and treating this as a business, investing in a tool that provides actual data will pay for itself through better keyword decisions on every book you publish.