How Many Keywords Does Amazon KDP Allow?

Seven. Amazon KDP gives you seven keyword fields per title, each accepting up to 50 characters including spaces. Each field takes a phrase, not a single word — so you have seven phrases, not seven words. They're optional, and you can change them at any time after publication.

The longer version

The seven fields are the "backend keywords" — invisible to readers, used by Amazon to match your book to searches and, in some cases, to place it into additional browse categories beyond the three you select manually.

The most common mistake is treating them as seven single words. Fifty characters is room for a phrase like small town enemies to lovers romance (36 characters), which matches how readers actually search. Filling a field with the single word romance wastes roughly 43 characters and competes on the most contested term in the store.

What to put in them

Think in terms of what a reader types when they don't know your book exists:

Reader-language descriptions: slow burn workplace romance
Trope and subgenre terms: found family fantasy, cozy witch mystery
Situation and setting: victorian london detective novel
Audience: books for fans of dark academia
Comparable-title language, without naming a trademarked series
Problem or need, for non-fiction: how to stop procrastinating at work

What to leave out

Amazon's own guidance rules several things out, and some actively hurt you:

Words already in your title, subtitle, series name or author name. These are already indexed. Repeating them wastes a field
Your own categories — also already indexed
Other authors' names or trademarked series titles. Against KDP's terms and a takedown risk
Misspellings. Amazon handles these
Subjective claims — bestselling, award-winning, new
Time-sensitive terms — 2026, new release
Quotation marks, which narrow rather than broaden matching
Repeated words across fields. Terms combine automatically; you don't need romance book and romance novel

The part most authors don't realize

Keywords are editable after publication, and changing them costs nothing. So are categories. A book that's underperforming because it's described in author-language rather than reader-language is a fixable problem, not a permanent one.

A reasonable practice: review keywords at 30 days, then quarterly. Change a few at a time rather than all seven, so you can tell what moved.

Categories are separate

Distinct from keywords, and often confused with them. KDP allows you to select three categories per format. The option to email KDP support for additional categories was removed in 2023, so three is now firm.

Keywords and categories interact: Amazon may place a book into additional browse categories based on backend keywords, which is the only remaining route past the three-category limit.

Common exceptions

Character limits are per field, not total. Seven fields × 50 characters ≈ 350 characters of keyword space.
Some categories require specific keywords to qualify for them — certain romance and fantasy subcategories among them. Amazon documents these.
Other retailers differ. Kobo, Apple Books and Draft2Digital have their own keyword fields and limits; don't assume seven everywhere.
Ebook and paperback are separate records with their own keywords and categories. They don't have to match, though usually they should.

Sources

Amazon KDP Help, "Keywords" and "Categories" — field limits and prohibited content.

Platform limits change. Verified 9 August 2026.