Seven fields, 350 characters — should you use all of them? And are there ways to extend your keyword coverage beyond the official limits?
| 8-minute read | Beginner | Updated March, 2026 |
The question “how many keywords does my book need?” has a direct answer and a more useful answer. The direct answer: seven fields, each up to 50 characters. That is your allocation. The more useful answer: you should use all seven fields at or near their character limit, because every unused field is wasted discoverability potential. For the full keyword strategy, see our complete guide to Amazon KDP keyword research.
The Direct Answer
KDP gives you exactly seven keyword fields per book. Each field accepts up to 50 characters. You cannot add more fields than seven. The total keyword space is 350 characters — every character you leave empty is keyword coverage you are not claiming.
Why You Should Use All Seven Fields
Each field you leave empty is a lost opportunity to rank for an additional search phrase. Many authors leave two or three fields empty because they “ran out of keywords” — which is almost always a sign of insufficient research rather than genuine exhaustion of relevant phrases for their book.
Every book has more than seven relevant keyword phrases available to it. A cosy mystery novel has subgenre terms, setting terms, protagonist type terms, tone terms, series terms, period terms, and gifting terms — more than enough to fill seven fields with genuinely distinct, non-overlapping phrases. The challenge is researching and finding them, not the availability of keywords.
How to Fill Every Character
Filling each field to near its 50-character limit without padding or repetition requires treating each field as a slot for a different keyword cluster. Pack each field with a complete multi-word phrase that covers a specific angle of your book’s searchability. Use all available characters — “cosy mystery English village retired teacher” (42 characters) is better than “cosy mystery” (12 characters) because it covers multiple search pattern variations simultaneously.
Extending Coverage Beyond the 7 Fields
Your seven backend keyword fields are not your only keyword coverage. Amazon also indexes:
- Your title and subtitle — the highest-weight keyword fields. Phrases in your title rank more strongly than the same phrases in backend fields.
- Your book description — indexed for keyword relevance. Naturally occurring keyword phrases in your description add search coverage without using backend field characters.
- Your categories — category placement acts as a relevance signal for category-related searches.
A book whose title, subtitle, description, and seven keyword fields all contribute different, non-overlapping keyword coverage has significantly more total search coverage than a book that only uses the seven backend fields effectively.
Quality Over Quantity
Seven highly targeted, accurately relevant, long-tail keyword phrases will outperform seven broad, generic, or misleading keywords every time. The number of fields is fixed at seven. The quality and targeting precision of those seven phrases is where the performance difference is made.
Use all seven fields. Fill them near their character limits. Make each phrase genuinely distinct. Make every phrase accurately describe your book. These four rules will make your seven-field keyword strategy as effective as it can be.
KDP Rank Fuel by Vappingo‘s Listing Generator produces a complete, optimised listing from a single sentence — including all seven keyword fields filled near their character limits with distinct, research-backed phrases calibrated to your specific book.
Your keyword coverage brings readers in. Manuscript proofreading for KDP authors from Vappingo ensures the book those readers find is worthy of their five-star review.
