Free tool

Break-even ACoS for a series, not a single book

The usual rule says break even at your royalty rate, 70% for most ebooks. That ignores Kindle Unlimited page reads and every later book a new reader goes on to buy or borrow. Put in your series numbers to see the real line.

Your true break-even ACoS

291%

Below this ACoS, ads on book 1 make money across the series. The standard answer, your royalty rate, is 70%.

One buyer is worth

$7.30

$3.49 now + $3.81 in later books

One KU reader is worth

$4.80

$2.15 for book 1 + $2.65 later

Max cost per click

$0.58

At 10 clicks per reader, to break even

Later books per reader

1.10

Expected starts of books 2+

These are averages from your own read-through. Use the analyzer on your search term report to see which keywords actually hit them.

Book 1 priceClicks per reader

KU readers per saleYour report has no page reads. From your KDP dashboard: KU full reads of book 1 ÷ sales of book 1.Royalty on a sale%70% for ebooks priced $2.99-$9.99.KENP rate/pagePaid per page read. Changes monthly; use your latest from KDP reports.Book 1 KENPCPage count in KENP, from your KDP Bookshelf (Promote and Advertise).Books in seriesIncluding book 1.Read-through to book 2%Book 2 reads ÷ book 1 reads.Read-through after that%Typical carry-over between later books.Royalty per later book$What you earn per sale of books 2+.KENPC of later booksAverage page count in KENP.Target true ACoS%100% = break-even. 80% keeps 20% of series royalties as profit.

How the number is worked out

A buyer earns your royalty on book 1, plus your later-book royalty times the expected number of later books they start. A KU reader earns book 1's KENPC times the KENP rate, plus the same read-through applied to later books' page counts. Your break-even ACoS is everything one ad-driven sale (and the KU readers that come with it) earns, divided by the book 1 price.

Read-through compounds: with 45% going on to book 2 and 80% carrying on after that, a four-book series gives each new reader about 1.1 later books. That's why series authors can bid far above the single-book break-even. Get your own read-through from the read-through calculator and the current rate from the KENP rate page.

Then check it against real keywords

An average hides the keywords that lose money and the ones that quietly make it. Run your search term report through the analyzer to see each one.

Run your own report through the Kindle Author Ads Analyzer

Free, runs in your browser, no signup. See which terms to negate, which bids to move and which keywords pay across the series.

Analyze my report

Questions

What is the break-even ACoS formula?

For a single book: break-even ACoS = royalty ÷ price, so a 70% royalty breaks even at 70% ACoS. For a series: (everything one ad-driven sale and its KU readers earn across the series) ÷ book 1 price.

Why is my series break-even ACoS over 100%?

Because the ad report only counts book 1 sales at list price, while your real return includes KU page reads and later books. When those are worth more than the book 1 price, break-even ACoS goes above 100%.

What numbers do I need?

Book 1 price and royalty rate, KENPC of your books, the current KENP rate, read-through to book 2 and after, royalty per later book, and roughly how many KU readers you get per sale.

Should I aim for exactly break-even?

No. Set a target below break-even so ads leave a profit, then judge each keyword against it. The analyzer uses a target true ACoS (80% by default) for this.