How KDP keywords work
When you publish on KDP you get seven keyword boxes, each holding up to 50 characters. Amazon uses them, along with your title, subtitle, author name and categories, to decide which searches your book appears in. Readers never see them.
Use the boxes for what your title doesn't already say: themes, setting, character types, the reader's problem, the occasion it's bought for, comparable moods.
Long-tail phrases
A long-tail keyword is a longer, more specific phrase that a reader actually types, such as "ai for complete beginners" rather than just "ai". Fewer people search each one, but far fewer books compete for it, and the people who do search it are looking for exactly your book.
It's fine for a phrase to repeat a word from your title. In a test of 120 books by Kindlepreneur, reusing title words in the keyword boxes didn't lead to any penalty, and phrases entered the way readers type them ranked better than the same words scattered about. What matters is that each box adds something new.
Worked example
Title: AI for Beginners. Subtitle: A Plain English Guide to ChatGPT.
| Box | What it adds | Verdict |
|---|---|---|
| ai for newbies | newbies | Good: a real search phrase with a new word |
| chatgpt prompts for small business | prompts, small, business | Good: a specific audience |
| beginners guide ai | Nothing | Wasted: every word is in the title or subtitle |
| best new ai book | Nothing allowed | Wasted: quality claims and "new" aren't allowed, and "book" is in every listing |
What KDP asks you to avoid
- Information already in your title, contributors or categories (fine inside a phrase, wasted on its own)
- Claims about quality, such as "best" or "bestseller"
- Time-sensitive words: "new", "on sale", "available now"
- Words common to every listing, like "book"
- Spelling mistakes, and spacing, punctuation, capitalisation or plural variants of the same word
- Other authors' names, brands you don't own, and Amazon programme names such as "KDP Select"
- Quotation marks and HTML
KDP has a zero-tolerance policy for metadata meant to advertise, promote or mislead, so it's worth getting this right.
Phrases or single words?
Use both. A few boxes with specific descriptive phrases, and the rest with words and short phrases that describe your niche, setting, themes and reader. Put words in the order people search them. Amazon also matches the words in a box in other orders, so you don't need every variation.
Finding keywords to try
This tool checks the keywords you've chosen. To find them in the first place, start typing ideas into Amazon's search bar and note the suggestions it offers, look at the language readers use in reviews of similar books, and search your ideas on Amazon to see whether the results are books like yours. Our guide on how to find KDP keywords for free walks through it.
Common mistakes
- Seven single words. One-word boxes like "thriller" compete with every thriller on Amazon. A phrase such as "psychological thriller unreliable narrator" reaches readers who want exactly that.
- Leaving boxes empty. Every empty box is a set of searches your book can't appear in.
- Copying the title. A box that only repeats your title adds nothing: those words are already searchable.
- Keywords that don't match the book. Appearing in a search your book doesn't suit brings clicks that don't turn into sales. KDP also warns against misleading metadata.
Questions
Can I change keywords after publishing?
Yes. KDP lets you change keywords and your description as often as you like.
Should I use the same keywords for the ebook and paperback?
KDP recommends keeping keywords and descriptions consistent across formats.
Do I need commas between words?
No. Write each box as a phrase, the way a reader would type it.
Based on KDP's keyword guidance and Kindlepreneur's published keyword test, checked 28 October 2026.