KDP Ads Break-even ACOS Calculator

Amazon ads can grow your book sales, but they can also quietly lose money. This free calculator shows your break-even ACOS, the most you can pay per click, and whether your current ads make a profit.

How to use this calculator

  1. Enter your book’s list price.
  2. Enter your royalty per sale. Use the Royalty Calculator if you are not sure.
  3. Enter your average cost per click (CPC).
  4. Enter your click-to-sale rate as a percentage.

Key terms explained

ACOS (Advertising Cost of Sales): ad spend divided by ad sales, shown as a percentage.

Break-even ACOS: your royalty divided by your list price. If your ACOS is below this number, your ads are profitable. Above it, they lose money.

Cost per sale: CPC divided by your conversion rate. A $0.45 click with a 10% conversion rate costs $4.50 per sale.

Max CPC to break even: royalty multiplied by conversion rate.

Example: A $12.99 book with a $3.50 royalty has a break-even ACOS of about 26.9%. With a $0.45 CPC and a 10% conversion rate, each sale costs $4.50 in ads, which is $1.00 more than the royalty. That campaign loses money.

How to improve your ad results

  • Lower bids on keywords that get clicks but no sales.
  • Improve your cover, title and description to raise conversion.
  • Raise your price if your market allows it, which raises both royalty and break-even ACOS.
  • Remember that ads can also lift organic sales and series read-through, so some authors accept a small loss on book one.

Related tools: [Royalty Calculator], [Income Goal Calculator].

FAQ

What is a good ACOS for KDP ads?

A good ACOS is any value below your break-even ACOS. For many books that falls roughly between 20% and 50%, but it depends on your price and royalty.

How do I calculate break-even ACOS?

Divide your royalty per sale by your list price and multiply by 100.

What conversion rate should I expect?

It varies a lot by genre, cover and price. Many books see single-digit to low double-digit percentages, so use your own campaign data.

Should I stop an ad that loses money?

Not always. If the book starts a series, the loss may be repaid by later books. Otherwise, lower bids or pause the keywords that do not convert.

Why is my real ACOS different from the calculator?

The calculator uses averages. Real results change by keyword, season and competition.

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