Amazon ads are the most common paid tool for self-published authors, and one of the most common ways authors lose money. The console is the same one product sellers use, but the economics of a book are different. Royalties are small per sale, Kindle Unlimited reads complicate the numbers, and the value of a reader often lies in the books they buy next.
This guide covers Amazon advertising for KDP authors from the ground up: the math that decides whether ads can work, how to set up and target campaigns, how to manage budgets, and how to measure results across a series.
Start with the royalty math
Everything begins with what you earn per sale. KDP ebook royalties are either 70 or 35 percent of the list price depending on the option and price band you qualify for. Paperback royalties are a share of list price minus printing costs. Work out the actual amount you keep per copy in each format.
That amount is your break-even ad cost per sale. If you keep a small amount per ebook, your ads must produce a sale for less than that, or you lose money on the sale itself. Divide royalty by price to get a break-even ACoS for the book. The guide to a good ACoS explains the same calculation for products.
Count the whole series
For a standalone book, the royalty math is the whole story. For a series, it is not. A reader who buys book one at a loss may buy books two, three and four at full royalty.
Estimate read-through from your own sales: of the readers who buy book one, roughly what share go on to book two, and from two to three? Multiply through to get the expected royalty from one new reader across the series. That number, not the first book's royalty, is what an ad on book one can afford to spend.
Be conservative. Read-through estimates from a small number of sales are noisy, and they can drop when you advertise to a broader audience than your organic readers.
Remember Kindle Unlimited
If your ebook is in KDP Select, a share of readers will borrow it through Kindle Unlimited rather than buy it. You earn from pages read rather than from a sale. Depending on the report you use, those reads may not be included in the sales figure behind ACoS, which makes ads look worse than they are.
Track page reads alongside sales during ad campaigns, and include an estimate of page-read royalties when judging results. A campaign with poor ACoS and strong page reads may be profitable.
Setting up campaigns
Authors advertise through the Amazon Ads console, which KDP links to from your bookshelf. Sponsored Products are the core format for most authors: ads that appear in search results and on other books' pages. Other formats may be available depending on your marketplace and account.
A simple starting structure for one book:
An automatic campaign, to discover which searches and books Amazon matches you to.
A keyword campaign targeting genre terms, tropes and comparable author names.
A product targeting campaign aimed at specific comparable books.
Keep them separate so you can see which approach works for your book. Auto versus manual campaigns explains the split.
Targeting that works for books
Comparable authors and titles are usually the strongest targets. Readers stick to what they like, and a reader looking at a book similar to yours is a likely buyer. Pick authors and books close to yours in genre, tone and audience, not just the biggest names in the category.
Genre and trope keywords catch readers browsing for a type of story rather than a specific title. They tend to be broader and may need tighter bids.
Your cover and description matter more than the targeting. A book ad shows a thumbnail cover, a title and a rating. If the cover does not signal the genre at a glance, clicks will be low, and if the description does not hook, conversions will be. Listing optimization before ads applies to book pages as much as to products.
Budgets and bids
Book royalties leave little room for expensive clicks. Start with modest bids and a daily budget you would be comfortable losing while you learn. Raise bids only on targets that produce sales or page reads at an acceptable cost.
Give targets time. Books often sell at lower conversion rates than everyday products, so a target needs a fair number of clicks before you judge it. Pause targets that spend steadily without results, and add irrelevant search terms as negatives. Amazon PPC on small budgets covers how to stretch a limited budget.
Watch the hours too. Readers browse and buy at particular times, often evenings and weekends. If your hourly data shows certain hours spend without sales, concentrating budget in the hours readers buy can make a small budget go further.
Measuring across the catalog
Judge ads at the level of the series and the catalog, not only the campaign. Compare total royalties, including page reads and later books, over the weeks when ads ran against a similar period without them. If total royalties rise by more than ad spend, the ads are working even if individual campaign ACoS looks high.
Review monthly. Book sales are often slower and lumpier than product sales, and daily numbers move too much to act on.
Frequently asked questions
Are Amazon ads worth it for self-published authors?
They can be, especially for authors with a series, a strong cover and a genre with active readers. A single standalone book at a low price is harder to make profitable on ads alone. Work out what a new reader is worth across all your books before judging a campaign.
What is a good ACoS for Amazon book ads?
It depends on your royalty and your series. A standalone book needs an ACoS below the royalty it earns on each sale. A first-in-series book can run well above that if enough readers go on to buy later books. Set the target from your own numbers, not from a general rule.
What should authors target in Amazon ads?
Start with comparable authors and titles that readers of your book also read, plus keywords describing your genre and tropes. Run them in separate campaigns, give each a small budget, and keep the targets that produce sales and page reads.
Off Hours runs dayparting and budget rules on Amazon Ads campaigns, with free spend alerts, so a small book budget goes to the hours readers actually buy. Start a free 14-day trial.