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ROAS to ACoS converter

ACoS and ROAS describe the same thing from opposite sides. ACoS = 100 ÷ ROAS, and ROAS = 100 ÷ ACoS. Type either number below to convert it.

ROAS ↔ ACoS converter

ACoS → ROAS

ROAS
4.00

ROAS → ACoS

ACoS
20.0%

The formula

ACoS from ROAS
ACoS (%) = 100 ÷ ROAS
ROAS from ACoS
ROAS = 100 ÷ ACoS (%)

Amazon Ads reports both. Sponsored Products shows ACoS by default, while many other ad platforms and Amazon DSP talk in ROAS. Converting lets you compare targets across channels.

Because they are reciprocals, small ACoS changes at the low end move ROAS a lot: going from 10% to 8% ACoS takes ROAS from 10.0 to 12.5, while going from 50% to 48% only moves ROAS from 2.0 to about 2.08.

Worked example

  1. Your target is a 25% ACoS. ROAS = 100 ÷ 25 = 4.0.
  2. An agency reports a 5.0 ROAS. ACoS = 100 ÷ 5 = 20%.

A 25% ACoS is a 4.0 ROAS; a 5.0 ROAS is a 20% ACoS.

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Frequently asked questions

How do I convert ROAS to ACoS?

Divide 100 by ROAS. A ROAS of 4 equals a 25% ACoS; a ROAS of 2.5 equals a 40% ACoS.

Is a higher ROAS always better?

Higher ROAS means more efficient ads, but pushing ROAS too high can mean you're under-bidding and missing profitable sales. Aim for the ROAS that matches your target ACoS.

What ROAS is break-even?

Break-even ROAS = 100 ÷ break-even ACoS. If your break-even ACoS is 40%, your break-even ROAS is 2.5.