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ACOS Calculator

Calculate your Advertising Cost of Sale (ACOS) and compare it with the break-even and target ACOS your book's royalty can support.

Your Inputs

$
$

Sales revenue your ad report credits to ads.

Uses your royalty to work out the highest ACOS your book can afford.

$
$

Find it with the KDP Royalty Calculator.

$

Leave blank or 0 to target break-even.

Your Results

ACOS
25%
$120.00 spend on $480.00 sales
Break-even ACOS
33.29%
Royalty ÷ book price
Target ACOS
26.62%
Keeps your desired profit per sale
Pass: Profitable

Your ACOS is below your break-even ACOS (and at or below your target), so ad sales are earning more royalty than they cost.

About the ACOS Calculator

ACOS is the headline metric in Amazon Ads: the percentage of ad-attributed sales you spent on advertising. An ACOS of 25% means you spent $25 for every $100 of sales the ads generated. On its own, though, ACOS cannot tell you whether you are making money.

For books, the answer depends on your royalty. Your break-even ACOS is your royalty per sale divided by your list price. A paperback priced at $14.99 that pays you $4.99 per copy breaks even at about 33.3% ACOS. A Kindle eBook priced at $4.99 that pays about $3.40 at the 70% option can afford an ACOS near 68%. The same 40% ACOS is a loss on the first book and comfortable profit on the second.

This calculator gives you your ACOS, then optionally works out your break-even ACOS and a target ACOS that leaves the profit you want on each sale. A clear status tells you whether you are profitable, profitable but above target, at break-even or losing money. If you need your royalty first, use the KDP Royalty Calculator.

How It Works

ACOS is ad spend divided by ad-attributed sales, shown as a percentage.

Break-even ACOS is your royalty per sale divided by your book price. At that ACOS, the royalty from each ad sale exactly pays for the ads that produced it.

Target ACOS subtracts the profit you want to keep from your royalty before dividing by the price. If your ACOS is at or below target, you are earning at least that profit per ad sale on average.

Formula

ACOS
ACOS = Ad spend ÷ Ad-attributed sales
Break-even ACOS
Break-even ACOS = Royalty per sale ÷ Book price
Target ACOS
Target ACOS = (Royalty per sale − Desired profit per sale) ÷ Book price

Example

$120 spent, $480 in ad sales, $14.99 paperback earning $4.99 per sale, $1.00 desired profit

  1. ACOS: $120 ÷ $480 = 25.00%.
  2. Break-even ACOS: $4.99 ÷ $14.99 = 33.29%.
  3. Target ACOS: ($4.99 − $1.00) ÷ $14.99 = 26.62%.
  4. 25.00% is below both the target and the break-even ACOS.

The campaign is profitable and beating the target, so each ad sale is leaving more than $1.00 of profit on average.

Important Notes

  • ACOS uses sales at list price as reported by Amazon Ads, not your royalty.
  • Amazon counts sales within an attribution window after a click, so ACOS can change for several days after the period ends.
  • Kindle Unlimited page reads are not counted as ad sales, so ACOS can look worse than your true return for KU-enrolled books.
  • Break-even ACOS assumes a single format and price. If ads sell a mix of eBook and paperback, use a blended royalty and price.

Frequently Asked Questions

What is a good ACOS for books?

There is no universal good ACOS. A good ACOS is one below your break-even ACOS, which is your royalty divided by your price. Low-royalty paperbacks often break even around 25% to 40%, while 70% royalty eBooks can break even far higher.

Why is my break-even ACOS so low for paperbacks?

Printing costs come out of every paperback sale, so your royalty is a smaller share of the list price than with an eBook. A smaller royalty share means a lower ACOS ceiling.

Can ACOS be over 100%?

Yes. It means you spent more on ads than the ads brought in sales. That is always a loss on the ad sales themselves, though some authors accept it briefly for launches or to drive series read-through.

What is the difference between ACOS and TACOS?

ACOS compares ad spend with ad-attributed sales only. TACOS compares ad spend with all your sales, including organic ones. Use the [TACOS Calculator](/tools/tacos-calculator) to see how dependent your book is on ads.

How do ACOS and ROAS relate?

They are inverses. ROAS is sales divided by spend, so a 25% ACOS equals a 4.00x ROAS. The [ROAS Calculator](/tools/roas-calculator) converts between them.

What should I set as desired profit per sale?

Whatever you need each ad sale to contribute, for example toward editing or cover costs. Leave it blank to target pure break-even, which can make sense when you value rank, reviews or series read-through.

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