Amazon Ads ACoS Calculator
Your break-even ACoS for book ads
Amazon book ads only make sense if you know your break-even point. ACoS, advertising cost of sale, is the percentage of your revenue spent on ads. This tool shows your ACoS and, critically, the break-even ACoS you must stay under to make a profit on each sale.
What is ACoS?
ACoS stands for Advertising Cost of Sale, the ratio of ad spend to sales revenue from those ads, shown as a percentage. If you spend $10 on ads to make $40 in sales, your ACoS is 25%. Lower is better, but the number only means something once you compare it to your break-even ACoS.
What is a good ACoS for books?
It depends entirely on your royalty margin. Your break-even ACoS equals your royalty divided by your price. If your book sells for $4.99 and you earn $3.44 royalty, your break-even ACoS is about 69%, so anything below that is profit on the ad itself, before read-through and series sales are counted.
Why does read-through change the maths?
For a series, a single ad-driven sale of book one can lead to sales of the whole series at no extra ad cost. That means you can profitably run ads above the single-book break-even ACoS, because the true return includes the later books. Authors with strong series read-through can bid far more aggressively.
Frequently asked questions
What is ACoS?
Advertising Cost of Sale: the percentage of your sales revenue spent on ads. Spend $10 to make $40 and your ACoS is 25%.
What is a good ACoS for book ads?
Anything below your break-even ACoS, which is your royalty divided by your price. Series read-through lets you go higher.
How do I calculate break-even ACoS?
Divide your royalty per sale by your list price. A $3.44 royalty on a $4.99 book is about 69%.
Is this free?
Yes, and it runs in your browser.