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Amazon ACoS Calculator

Calculate Amazon ACoS, convert it to ROAS, and compare ad spend with your break-even margin.

Example: $500
$
Example: $2,500
$
Example: 35%
%

Use the margin left after product, marketplace, fulfillment, and other non-ad variable costs.

Review the result

Amazon ACoS
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ROAS equivalent
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Break-even ACoS
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Profit after ads
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Max ad spend at current sales
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How to use this calculator

Calculate ACoS from attributed sales

ACoS shows the share of ad-attributed sales spent on advertising. Use spend and sales from the same campaign scope and reporting period so the ratio stays meaningful.

Compare ACoS with contribution margin

Your break-even ACoS is approximately the contribution margin available before ads. If ACoS is above that margin, the attributed sale does not cover the entered non-ad costs and ad spend.

There is no universal good ACoS

A launch campaign, a profit campaign, and a brand campaign can need different targets. Use your unit economics and campaign goal instead of an unsupported industry threshold.

Formula quick reference

  • ROAS = ad-attributed sales / ad spend
  • ROAS = 100 / ACoS percentage
  • Break-even ACoS = pre-ad contribution margin percentage
  • Profit after ads = ad-attributed sales x pre-ad margin - ad spend
  • Maximum ad spend at current sales = ad-attributed sales x pre-ad margin

Worked example

Amazon PPC example

Inputs: $500 ad spend, $2,500 attributed sales, and a 35% pre-ad contribution margin

Result: 20% ACoS, 5x ROAS, and $375 profit after ads

Note: The break-even ad spend at the same sales level is $875.

Common mistakes

  • Comparing spend and sales from different date ranges or attribution windows.
  • Using gross revenue margin without marketplace, fulfillment, or refund costs.
  • Treating a low ACoS as the only campaign objective.

What the result means

  • Amazon Ads states that a good ACoS has no single definitive value.
  • Use your own contribution margin and campaign objective as the decision boundary.

Source notes

  • Amazon Ads defines ACoS as ad spend divided by ad-attributed sales, expressed as a percentage.
  • Amazon Ads describes ROAS as ad revenue divided by ad spend and notes that break-even ACoS is linked to profit margin.

Amazon ACoS Calculator FAQ

How is Amazon ACoS calculated?

Divide Amazon ad spend by ad-attributed sales, then multiply by 100.

How do I convert ACoS to ROAS?

ROAS is the inverse ratio. Divide 100 by the ACoS percentage, or divide attributed sales by ad spend.

What is break-even ACoS?

It is the ACoS at which the contribution left before ads is fully used by advertising. It is approximately equal to your pre-ad contribution margin percentage.

What is a good Amazon ACoS?

There is no universal number. A workable target depends on margin, campaign purpose, growth stage, and how sales are attributed.

Is ACoS the same as TACoS?

No. ACoS divides ad spend by ad-attributed sales. TACoS divides ad spend by total sales, including organic sales.