How to choose book categories and keywords

What categories and keywords do

When you publish a book, the store needs to know where to put it and when to show it. You tell it with two kinds of information:

• Categories are the shelves. A reader browsing "Historical Mystery" or "Personal Finance" sees books placed there.
• Keywords are extra search terms. They help the store match your book to what readers type into the search box.

Together with your title, subtitle and description, they decide whether the right readers ever see your book. Getting them right doesn't sell a weak book. Getting them wrong can hide a good one.

Start with comparable books

Pick a handful of recent books that your readers probably also enjoyed. Look at each one's store page. Note:

• The categories it appears in (many store pages list them, or show where it ranks).
• The words in its title, subtitle and description.
• How specific its genre is. "Fantasy" or "Cozy fantasy with a found family"?

Patterns will appear. Those patterns are where your readers already look.

Choosing categories

On Amazon KDP you choose categories as part of setting up the book, and other stores have their own version of the same step. Check the current KDP help pages for how many you can pick and how the selection works, because it has changed over the years.

A few principles hold everywhere:

• Accuracy beats strategy. It's tempting to pick an obscure category where it's easy to rank. But a thriller placed in a category for, say, travel guides reaches readers who don't want it. They don't buy, or they buy and leave confused reviews. Stores can also move books that are clearly in the wrong place.
• Specific beats broad. "Fiction" is a warehouse. "Psychological thrillers" is a shelf. Choose the most specific category that honestly fits.
• Match the reader's expectation. If a reader would be surprised to find your book on that shelf, it doesn't belong there.

Many stores and distributors outside Amazon use BISAC subject codes, a standard list of book subjects used widely in the US book trade. The same principles apply: pick the most accurate, specific codes.

Choosing keywords

Think about what a reader who would love your book actually types when they're looking for their next read. It's rarely the title of a book they've never heard of. It's usually a description.

For fiction, combine:

• Subgenre: cozy mystery, space opera, small-town romance.
• Tropes: enemies to lovers, chosen one, locked room.
• Setting: Victorian London, generation ship, Scottish island.
• Character type: female detective, retired soldier, witch.
• Mood: dark, heartwarming, funny, slow burn.

For nonfiction, think about the problem: "how to stop procrastinating", "budgeting for freelancers", "beginner sourdough". Readers search for their problem, not your book's title.

On KDP you add keywords in the book's setup, in a small set of keyword boxes. A box can usually hold a short phrase rather than a single word. Check the current KDP help pages for the exact number and length allowed.

Testing ideas

Type the start of a possible keyword into the store's search box and look at the suggestions that appear. Suggestions hint at what people really search for. Then search the phrase and look at the results. If the top books are like yours, it's a good fit. If they're nothing like yours, readers using that phrase want something else.

Don't trust any single tool or guess too much. You're looking for phrases that are both popular enough to matter and honest about your book.

What to avoid

KDP publishes guidelines on keywords, and other stores have similar rules. Read the current version, but these are common sense anywhere:

• Other authors' names or book titles. Don't put a famous author's name in your keywords. It's misleading, and it's against KDP's guidelines.
• Trademarks and brand names you don't own.
• Claims about quality or popularity, such as "bestseller" or "best".
• Time-sensitive or price words, such as "new" or "free".
• Anything inaccurate. A keyword that brings in the wrong readers costs you more than it gains.
• Repeating words already in your title or subtitle. They usually count already, so use the space for something new.

Your title, subtitle and description help too

For nonfiction especially, a clear subtitle does a lot of work. "A Practical Guide to Budgeting for Freelancers" tells both readers and the store what the book is. Don't stuff it with keywords, though. A subtitle that reads like a list of search terms puts readers off, and stores may ask you to change it.

For fiction, the description's first lines should make the genre obvious. That helps readers, and it's consistent with the categories you chose.

Revisit after launch

Categories and keywords aren't permanent. A few weeks after release, look again. Search your keywords and see whether your book appears and whether it sits among the right neighbours. Look at the "also bought" or similar recommendations on your page. They show which readers are finding you.

If the neighbours are wrong, adjust. Change one or two things at a time so you can tell what made a difference.

Doing this in Authr

Authr can't choose your categories for you, but it can help you see your book clearly. Open a brainstorm with agents that have read your chapters and ask them to list the tropes, setting and mood they found. Then check every idea in the store yourself. You decide what goes on the book's page.