KDP keyword research tool: plan your seven keyword slots
This free KDP keyword research tool checks the seven keyword boxes on your Amazon listing. It's a checker, not a database, so it won't show you search volume, a competition score or a list of suggestions. What it shows is what your seven boxes are wasting: words already sitting in your title, subtitle or author name, words repeated from one slot to the next, and words KDP doesn't allow.
It opens on a sample book with five phrases filled in. That sample has 16 useful terms and 2 wasted words, and the tool tells you two slots are still empty. Swap in your own title and phrases and the numbers move as you type. Below the tool you'll find a free research method, KDP's rules in plain words, and four worked listings.
How to use the keyword planner
The tool treats every word in those three boxes as already indexed.
characters used, plus any repeated, rejected or overly broad words.
Nothing is saved on this page, so copy before you leave or reload.
The three category boxes are notes for you. The tool doesn't read them.
A free KDP keyword research tool: what it checks and what it does not
Each slot has a meter that runs to 50 characters. It turns amber past 42.5 characters and red past 50, with a note such as "29 of 50 characters" or "52 characters, which is 2 over the limit". Here's a caveat worth knowing: KDP's keyword help only says to keep an eye on the character limit in the text field and never gives a number. Fifty is the figure authors commonly report, so the tool uses it. Check the box in your own dashboard as of 2026 before you trust any number, ours included.
The repeat check lowercases everything, folds accents, and splits on anything that isn't a letter, a digit, an apostrophe or a hyphen. Short joining words (a, an, the, and, or, of, in, on, for, to, with, by, at, from, is, it) are ignored. A light stemmer matches plain plurals, so "juan" catches "juans". A word counts as wasted if it's in your title, subtitle or author name, if an earlier slot already used it, or if it sits on one of the two lists below. If a word is wasted in several ways, it's still counted once for that slot.
The tool keeps two lists apart on purpose. The first is words KDP's guidelines don't allow: free, bestseller, bestselling, sale, new, amazon and kindle. KDP names "free," "bestselling," time-sensitive words such as "new" and "on sale," and Amazon program names, and the tool files its close cousins with them. The word "new" is let through when it's part of a place name, so "new mexico territory" passes. The second list is words KDP doesn't name but that waste a slot or invite trouble: best, discount, cheap, kobo, nook, audible, ebook and e-book. Those get a "usually a bad idea" note. A third short list (book, books, read, reading, author, novel, story, stories, writing) earns a "too broad to place you" note, and those words count neither as wasted nor as useful.
A useful term is a word that's not in your listing, not on any list and not a joining word, counted once however often you repeat it. The verdict pill reads "slots still empty" until all seven are filled, then red for more than four wasted words, amber for one to four, and green for none.
One plain sentence about the limits: the tool can't know what readers search for or how many of them do.
One plain sentence about the limits: the tool can't know what readers search for or how many of them do.
How to research keywords for free
This is the method KDP itself describes on its keyword help page, put into steps you can follow in an afternoon.
Write down how a stranger would ask for your book, not how a library would shelve it.
setting, character types, character roles, plot themes and story tone. Write two or three candidates for each.
If the results look irrelevant or unsatisfying for your book, change the phrase. That's KDP's own test.
KDP's example is that customers search for "military science fiction" and probably not "fiction science military".
You can change keywords as often as you like, and category changes can take up to 72 hours to show.
Paid tools that estimate search volume exist, and we don't review them here. A free routine like this is plenty for a first listing.
Worked examples
Every figure below came from running the tool's own code. The book is the tool's sample, an invented novel called The Long Winter Count, with the subtitle "A Novel of the San Juans" and the author name Ana Beltrán.
Example A is the sample exactly as it loads. The five phrases run 29, 27, 24, 29 and 24 characters, 133 in all, out of 350 available across seven boxes (38.0 percent). The tool finds 16 useful terms: 1890, snowbound, mining, town, mystery, colorado, historical, fiction, mountain, frontier, women, survival, silver, rush, western and saga. It finds 2 wasted words, "san" and "juan" in slot 3, because "San Juans" is in the subtitle. Slot 4 gets a "too broad" note for "story". The pill says two slots are still empty.
Example B is a bad listing, slot by slot.
| Slot | Phrase | Characters | What the tool flags | Wasted |
|---|---|---|---|---|
| 1 | best western novel ever | 23 | "best" is a bad idea; "novel" is in the subtitle | 2 |
| 2 | long winter count | 17 | all three words are in the title | 3 |
| 3 | winter novel | 12 | both words are in the listing and repeated from earlier slots | 2 |
| 4 | free kindle western | 19 | "free" and "kindle" not allowed; "western" repeated | 3 |
| 5 | historical fiction | 18 | nothing | 0 |
| 6 | colorado historical fiction mystery | 35 | "historical" and "fiction" repeated from slot 5 | 2 |
| 7 | silver rush | 11 | nothing | 0 |
That's 135 characters, 8 useful terms and 12 wasted words (2 + 3 + 2 + 3 + 0 + 2 + 0), so the pill goes red: "A lot of the seven is being spent twice."
Example C is the fix, with all seven slots filled: "gold rush western" (17 characters), "schoolteacher survival" (22), "colorado historical fiction" (27), "snowbound mining town mystery" (29), "frontier women" (14), "1890s mountain village" (22) and "silver saga" (11). That's 142 characters, 40.6 percent of the 350, with 19 useful terms and no wasted words. The pill turns green. Change slot 6 to "1890s mountain town" and slot 7 to "silver rush saga" and it drops to amber with 2 wasted words, because "town" now repeats slot 4 and "rush" repeats slot 1.
Example D is three small checks of the matching rules. Typing "juans" into a slot flags it against the subtitle, because plurals are matched. Typing "beltran family saga" flags "beltran", because accents are folded away. Typing "new mexico territory" raises nothing, while "new western" is flagged. The stemmer is light, though, so an irregular pair such as "wolf" and "wolves" isn't matched even though KDP treats plural variants as redundant. That's why this is a first pass and not a verdict.
The point of all four: a green pill means nothing is wasted. It doesn't mean the phrases are good ones.
KDP's rules for keywords and categories
These come from KDP's own help pages, read in October 2026. Check KDP's guide to keywords and the KDP metadata guidelines for books before you publish, because platform rules change.
The keyword help page says to use up to seven keywords or short phrases. On single words versus phrases, KDP's two pages don't quite agree. The keyword help says single words work better than phrases, and specific words better than general ones. The metadata guidelines say keywords can be a word or a phrase, and recommend phrases of two to three words for best results. The tool's side note follows the keyword help and suggests testing both in Amazon's search bar, and we'd do the same. Put the words in the order a customer would type them.
KDP's lists include other authors and their books, sales rank claims such as "bestselling," advertising or promotions such as "free," anything unrelated to the book, HTML tags, quotation marks, Amazon program names, brands you don't own, time-sensitive words such as "new" and "on sale," and information common to most books in the category, such as "book." Misspellings, plural variants and anything already in the title or contributor names are redundant. KDP says the list isn't exhaustive and that it doesn't tolerate keywords that mislead or manipulate customers.
You can pick up to three categories when you create a book, according to KDP's category help, and it can take up to 72 hours for the book to show in new ones. The KDP support team can't recommend specific categories. The keyword help also says not to repeat words already in your category names. The planner has three boxes for you to keep notes, and it doesn't check them. Our own advice is to choose the narrowest true category over the biggest one, since a smaller shelf gives a book a better chance of ranking near the top.
Common keyword mistakes
Repeating the title
A slot that restates your title or author name buys nothing, since those words are already searchable.
Single generic words
"Book" and "novel" describe every listing on the shelf. They help no one find yours.
Banned promotions
"Bestselling," "free," "new" and "on sale" are on KDP's not-allowed list.
Naming other authors
Other writers and their books are off limits as keywords, even when your readers love them.
Commas and quotation marks
Quotation marks only cost characters, and KDP says they limit a search to exact matches.
Off-story keywords
If a phrase doesn't match the book's central story, it earns you the wrong readers or none.
Using the boxes as a blurb
Seven keywords aren't a place for the description. Short phrases beat sentences.
Leaving two slots empty
An empty box earns nothing. Fill all seven, and make each one something different.
Tips by situation
Fiction
Think setting, era, tone and the reader's mood: "frontier women," "snowbound mining town," "cozy small town." Skip genre names that already appear in your category path, since KDP asks you not to repeat them.
Nonfiction
Name the reader's problem and the outcome in plain words, the way a person would type it into a search bar. If the topic is already in your title or subtitle, spend the slots on angles the title doesn't carry, such as the audience or the method.
Memoir
Use setting, period, the defining event and the relationship at the center of the story. A subject heading no reader would ever type, however accurate, won't help a stranger find you. Once they arrive, a strong bio helps, and the author bio builder will get you started.
Series and later editions
Keep keywords, description and categories consistent across paperback, ebook and audio. Revisit the boxes when book two arrives.
Related guides on the Author Resources hub
- How to self-publish on Amazon: the KDP form this tool sits beside, step by step.
- How to market a book: where keywords fit among the other ways readers find a book.
- How to launch a book: what to have set before the listing goes live.
When keywords are a marketing job
Once the seven boxes are clean, a listing still sells on its cover, its description and its reviews. We've been publishing books since 1996, and our marketing team can look at the whole listing with you, not only the metadata. Send us the listing and tell us what you want it to do, and a free quote comes inside 24 hours. For ebook listings in particular, our ebook marketing services page explains how we work.
Once the seven boxes are clean, a listing still sells on its cover, its description and its reviews.
Questions we get asked
Is there a free KDP keyword research tool?
Yes, this one is free, but it checks the seven boxes you've filled in rather than reporting search volume. For volume you'd need a paid tool, or the free routine above: type candidates into the Amazon search bar and see what it suggests.
How many keywords can I use on KDP?
KDP's keyword help says up to seven keywords or short phrases per book, as of 2026. Each box has a character limit, so shorter phrases fit more meaning into the same space.
How many characters fit in each KDP keyword box?
KDP says to keep an eye on the character limit in the text field and doesn't print a number on its help page. Authors commonly report 50, and the tool uses 50 for its meter. Check your own dashboard for the live figure.
What is the best keyword for my book?
No single word wins. Choose phrases a reader would really type, drawn from setting, character types, character roles, plot themes and story tone, and test each in Amazon's search bar. If the results look wrong for your book, change the phrase.
Should I repeat words from my title?
No. KDP lists information from your title and contributors among the keywords to avoid, and the tool counts those repeats as wasted words. Spend the slot on a term the title lacks.
Can I use author names or "bestselling" as keywords?
No. KDP rules out other authors and their books, sales rank claims such as "bestselling," and promotions such as "free." The tool flags those words so you can catch them before you publish.
How long until new keywords work?
KDP's keyword page doesn't give a number, and it points to a separate timelines page for new publications and updates. It does say you can change keywords as often as you like. Category changes can take up to 72 hours to show.
Why does the tool flag "kindle" or "ebook"?
"Kindle" is an Amazon program name and sits on the list KDP's guidelines don't allow. "Ebook" is on the tool's own "usually a bad idea" list: KDP doesn't name it, but it adds little in a keyword box.
Does the tool save my keywords or check categories?
Neither. Nothing you type is stored or sent anywhere, so copy your lines before you leave. The category boxes are notes only.
Keep going with the next tool
- Title and blurb workshop: the description and the keywords share one KDP form.
- ISBN checker: the identifier on the same form.
- Royalty calculator: the price step that follows.
- All author tools
Tools will only take you so far
Send what you have. Even a half-written manuscript is enough for a reader to tell you what it needs.