The Complete Guide to KDP Keyword Research

Amazon's A9/A10 algorithm matches search queries to products using a combination of text relevance and conversion signals. For books specifically, the algorithm considers:

- Keywords in your title, subtitle, and series name
- Your 7 backend keyword fields
- Your book's categories
- Review velocity and star rating
- Sales velocity and BSR rank
- Click-through rate from search results

Keywords in your title carry the most weight. Your subtitle is the second-most important keyword location. Backend keywords matter for long-tail and secondary terms. Reviews and sales velocity determine how aggressively Amazon promotes you for those keywords.

The practical implication: a book with a well-keyworded title and 15 reviews will rank higher than a book with a generic title and 100 reviews, for most long-tail searches.

The simplest and most powerful keyword research tool is Amazon's own search bar. Type a partial phrase and Amazon shows you the most-searched completions — these are real queries from real buyers.

Process:
1. Go to Amazon.com (in books department)
2. Type your main topic (e.g., "self-help for") and note the autocomplete suggestions
3. Try variations: add a word, change the word order, try synonyms
4. Type your genre + reader type ("mystery novels for beginners", "cozy mystery for cat lovers")
5. Record every relevant phrase — these are exact buyer search queries

Autocomplete tips:
- Work left to right: try one-word stems first ("ketogenic", "anxiety", "cozy") then progressively longer phrases
- Use letters: type "ketogenic a", "ketogenic b"... to surface every autocomplete variant
- Do this on both .com and your local storefront — they can differ

This process is free and requires no tools. Spend 30–60 minutes doing thorough autocomplete research before any other keyword work.

Your best-ranking competitors have already done keyword research for you. Here's how to extract their strategy:

1. Find competitors: Search Amazon for your main topic and note the books ranking in the top 10. These are your primary competitors.

2. Analyse their titles and subtitles: Write down every keyword phrase in the title and subtitle. Pay attention to specificity — "mindfulness" vs "mindfulness for anxiety" vs "mindfulness for teenagers with anxiety".

3. Browse their "Also Bought" section: The books that appear in "Customers who bought this also bought" define your book's niche neighbourhood. Their keywords are your keywords.

4. Read their reviews: Customer reviews contain the exact language your buyers use. "I bought this because I was struggling with..." tells you what problem your book should address in its description.

5. Check their categories: Scroll to the bottom of a competitor's product page. The categories listed there are eligible categories for your book too — and often reveal niche subcategories you hadn't considered.

Use Pubscout to see live BSR data on competitor books as you browse, so you can identify which competitors are actually selling (BSR under 50,000) vs. which are just ranking for search terms.

Your title and subtitle are your two most valuable keyword real estate. This is not licence to keyword-stuff — Amazon can penalise titles that read like keyword lists — but strategic keyword placement in natural titles is the most effective SEO lever you have.

Non-fiction title strategy:
- Main title: Clear benefit or topic (can include primary keyword)
- Subtitle: 1–2 additional keyword phrases + your USP or reader benefit
- Example: "The Anxiety Workbook: Daily CBT Exercises for Teens and Young Adults to Build Calm, Confidence and Resilience"

This subtitle contains: "anxiety workbook", "CBT exercises", "teens", "young adults", "calm", "confidence", "resilience" — all searchable terms.

Fiction title strategy:
- Titles don't need keywords the same way non-fiction does — your categories and backend keywords carry more weight
- Series name does factor in: "A [Location] [Occupation] Mystery" (e.g., "A Cotswolds Bookshop Mystery") signals genre clearly to both readers and the algorithm
- Subtitle for fiction: only use if your sub-genre benefits from clarification (e.g., "A Clean Western Romance")

What to avoid:
- Titles with 10+ words (hard to read as a thumbnail)
- Repeating the same keyword in both title and subtitle
- Generic titles without any keyword signal ("The Journey" = undetectable by the algorithm for any specific search)

KDP's 7 keyword fields (50 characters each) are your opportunity to capture long-tail searches that don't fit naturally in your title. Think of them as extended search index entries.

Best practices:
- Enter phrases, not single words ("books for overthinkers" not just "overthinking")
- Don't repeat title or subtitle words — Amazon already indexes those
- Fill every field to the character limit
- Include: reader intent phrases, theme/trope keywords, comparison phrases ("readers of [popular author] enjoy"), setting keywords, character type keywords

Fiction keyword examples (romance genre):
- "small town romance with grumpy hero"
- "clean cowboy romance series"
- "second chance love story standalone"
- "closed door Christian romance women"
- "forced proximity romance workplace"

Non-fiction keyword examples (fitness genre):
- "beginner workout plan no equipment"
- "strength training women over 50"
- "home fitness programme 4 weeks"
- "lose weight build muscle diet book"
- "body recomposition for beginners guide"

Use Amazon autocomplete research (from the previous section) to populate these fields — you're directly entering proven search terms.

Finding keywords is step one. Evaluating whether you can rank for them is step two.

The three signals to check:
1. Number of results: Search your target keyword on Amazon. Under 500 results = low competition. 500–2,000 = medium. 2,000+ = high.
2. BSR of the top 10: Are the top results actively selling (BSR under 50,000) or just ranking due to historical sales? Use Pubscout to see BSR on every search result page.
3. Review count of top 10: If the average review count of the top 10 results is over 200, you need momentum to break in. Under 50 average reviews = accessible for a new book.

The opportunity formula: Low result count + active BSR + low review count = keyword opportunity. Finding 5–10 such keywords before launch is more valuable than a list of 100 keywords where you can't realistically rank.

Amazon actively polices keyword abuse. The following practices violate Amazon's terms of service and can result in your book being suppressed or removed:

- Including other authors' names in your keywords or title
- Using competitor book titles as keywords
- Repeating the same word more than once across your keyword fields
- Misleading keywords that don't accurately describe your book
- Profanity or offensive terms

Beyond ToS violations, over-optimised titles that read as keyword lists damage your conversion rate — readers see through them, and low click-to-purchase rates suppress rankings over time.

The test: Would a genuine reader be confused or misled by your keywords? If yes, don't use them.

How many keywords should I use for my KDP book?

Use all 7 keyword fields and fill each one with a distinct long-tail phrase (not a single word). Each field can hold up to 50 characters. Focus on buyer-intent phrases rather than broad single keywords.

Can I change my KDP keywords after publishing?

Yes. You can update your keywords at any time through your KDP dashboard. Changes typically take 24–72 hours to take effect in Amazon search. Review your keywords quarterly against current autocomplete data.

Do keywords in my book description help with Amazon SEO?

Amazon's algorithm does index your book description for search, but it carries less weight than title, subtitle, and backend keywords. Focus your description on reader conversion rather than keyword density.

What's the difference between Amazon keywords and Google keywords?

Amazon keyword research is focused on buyer intent at the point of purchase — someone searching "cozy mystery cat amateur detective" is ready to buy a book right now. Google keywords are often informational ("what is a cozy mystery") and need content marketing approaches. Prioritise Amazon keyword research for KDP specifically.