KDP gives you seven keyword fields, each accepting up to 50 characters. That is 350 characters total to tell Amazon’s algorithm what searches your book should appear in. Most authors fill these fields poorly — with single words, repeated terms, or phrases that are already covered by their title. This article covers exactly how to use all 350 characters strategically. For the full keyword research strategy, see our complete guide to Amazon KDP keyword research.
The Seven Fields: An Overview
In KDP’s Book Details section, you will find seven input fields labelled simply “Keyword 1” through “Keyword 7.” They are identical in function — Amazon treats all seven equally and indexes the content of each. There is no documented difference in weight between field 1 and field 7.
Together, these fields form your book’s primary keyword targeting layer — the invisible metadata that tells Amazon which searches to show your book in. They are separate from your title, subtitle, description, and categories, all of which Amazon also indexes for keyword relevance. But the keyword fields exist specifically and solely for search optimisation, which means every character should be used as efficiently as possible.
The Rules That Govern Them
Amazon has specific rules about what can and cannot go in your keyword fields. Violating them can result in your metadata being rejected or your book being suppressed:
Prohibited content:
- Competitor author names or book titles — you cannot target readers of specific competing authors through your keywords
- Amazon programme names — “Kindle Unlimited,” “KDP Select,” “Prime Reading” are prohibited
- Misleading claims — “bestseller,” “free,” “#1 in” are not permitted in keyword fields
- Offensive or inappropriate terms
- Temporary or time-sensitive information — “summer 2025,” “new release”
- Information covered elsewhere in your metadata — Amazon’s guidance says not to repeat content from your title or categories, as it does not improve discoverability (more on this below)
Permitted content: Any accurate, relevant search phrase a reader might use to find a book like yours, including genre terms, subgenre terms, setting descriptors, character types, themes, tropes, moods, and audience identifiers. For the full list of prohibited terms, see our article on prohibited KDP keywords: what not to use.
How to Format Keywords Within Each Field
Each keyword field accepts up to 50 characters. You can use those 50 characters as:
- A single long phrase: “amateur sleuth cosy mystery English village cats” (46 characters) — Amazon indexes this as one phrase and also indexes any shorter sub-phrases within it
- Multiple shorter phrases: “cosy mystery 1950s detective retired teacher” — Amazon reads the words in order, so this works as both a full phrase and shorter combinations
- A combination approach: “small town romance enemies to lovers” — two distinct phrase concepts in one field
Separator rules:
- Use spaces between words — Amazon reads multi-word phrases correctly when words are separated by spaces
- Do not use commas as separators within a single field — commas may cause Amazon to read phrases incorrectly
- Do not use quotes around phrases — they are not necessary and consume character space
- Capitalisation does not affect indexing — “Cosy Mystery” and “cosy mystery” are treated identically
A Field-by-Field Strategy
Rather than thinking of seven separate keywords, think of seven separate keyword clusters — each targeting a different aspect of your book’s searchability:
Field 1 — Primary genre + subgenre phrase: Your most specific and most important genre description. “Amateur sleuth cosy mystery English village” or “slow burn enemies to lovers contemporary romance.”
Field 2 — Setting or period descriptor: Where and when your book is set, if that is relevant to reader searches. “1920s English countryside mystery” or “small town Texas romance” or “regency London historical fiction.”
Field 3 — Character type or trope: The protagonist type or the trope that defines the romantic or genre dynamic. “Retired librarian mystery protagonist” or “forced proximity workplace romance” or “reluctant hero fantasy quest.”
Field 4 — Mood or tone descriptor: The emotional experience your book delivers. “Heartwarming cosy mystery feel-good” or “dark psychological suspense unreliable narrator” or “laugh-out-loud romantic comedy.”
Field 5 — Audience or comparative identifier: Who the book is for, or who it is compared to. “Mysteries for women book club reads” or “fans of Richard Osman mystery series” — note that you cannot use competitor author names, so this is better framed as audience terms: “mystery readers who love British settings humour.”
Field 6 — Theme or content identifier: Specific themes, content elements, or subject matter. For fiction: “mystery with recipes bakery setting” or “fantasy magic system academy.” For non-fiction: “productivity system ADHD adults focus” or “freelance pricing negotiation strategy.”
Field 7 — Variant phrasing or secondary genre: Alternative ways readers might search for your book that are not covered by fields 1–6. If your cosy mystery also has romantic elements, this field might cover “cosy mystery with romance subplot.” If your non-fiction covers multiple audiences, the second audience goes here.
What Not to Put in Your Fields
Do not repeat your title keywords. If your title is “The Thornwick Cosy Mystery,” you do not need “Thornwick” or “cosy mystery” in your keyword fields — Amazon already indexes your title with higher weight than your keyword fields. Use the 50 characters per field for terms your title does not cover.
Do not repeat your category keywords. If your category is “British Detectives > Cosy Mystery,” you do not need “British detective cosy mystery” in a keyword field. You are already indexed for those terms through your category placement.
Do not use single words. A single word like “mystery” or “romance” generates enormous competition. You are not going to rank for “mystery” as a new book. Use those 50 characters for a specific multi-word phrase that you can realistically rank for.
Do not leave fields blank. Every unused field is wasted indexing potential. Even if your seventh field feels harder to fill, find a phrase — a variant subgenre term, a secondary audience identifier, a regional setting — rather than leaving it empty.
Pre-Publish Keyword Field Checklist
- All seven fields filled, each as close to 50 characters as possible
- No single-word keywords anywhere
- No repetition of title or subtitle keywords
- No repetition of category keywords
- No prohibited terms (competitor names, “bestseller,” Amazon programme names)
- Each field covers a different aspect of your book’s searchability
- All phrases accurately describe your book — no misleading keywords
- No commas used as separators within fields
Filling all seven fields with the right phrases — without repetition, without prohibited terms, covering all the relevant search angles for your specific book — is exactly what a dedicated keyword research tool for KDP like KDP Rank Fuel by Vappingo is built to help with. It generates 100 targeted keyword ideas from your book details, giving you far more than seven phrases to work with — so you can select the best seven from a well-researched pool rather than guessing under pressure at the publishing stage.
Once your keywords are bringing the right readers to your book, the manuscript needs to keep them. Novel proofreading from Vappingo ensures your book is error-free and publication-ready before those readers arrive.
