Convert ACoS to ROAS, reverse the calculation, and check break-even ACoS from your product margin — so you know whether Amazon Ads are actually profitable.
Updated Sep 26, 2025 · sources on every number
ROAS & ACoS calculator
Live · 2026
What your ads cost over the period.
Sales your ad platform attributes to the campaigns.
Contribution margin before ads: after COGS, marketplace/payment fees, shipping and other variable costs. Enter as % of attributed revenue.
Result
ROAS & ACoS
Return on ad spend
4.0×
ACoS is at or below break-even — the campaign breaks even or is profitable before fixed overheads.
Break-even ROAS: 3.3×
ROAS = revenue ÷ spend. ACoS = spend ÷ revenue.
Source:Amazon Ads · ads-math· Sep 26, 2025
Inputs restore automatically for an hour · this device only, nothing is sent anywhere.
01
Ad spend and attributed revenue from your ad platform, for the same period.
02
Use contribution margin after variable costs and before ad spend.
03
ROAS as a multiple of spend, ACoS as a percentage of revenue — the same fact twice.
04
Compare ACoS with the entered contribution margin; fixed overheads and input accuracy still matter.
They're the same relationship from two sides. ROAS is revenue ÷ ad spend — how many dollars of sales each ad dollar brings in. ACoS is ad spend ÷ revenue — what percent of your attributed sales went to ads. A ROAS of 4.0× is an ACoS of 25%.
The ACoS at which ad spend uses all of your contribution margin on attributed revenue. Enter margin after product, marketplace/payment fees, shipping and other variable costs, but before ads. A 30% contribution margin implies a 30% break-even ACoS and 3.33× break-even ROAS; this excludes fixed overheads and depends on correct inputs.
There's no universal number — the break-even point depends on your contribution margin. A 40% margin implies a 2.5× break-even ROAS before fixed overheads; a higher ROAS is above this simplified break-even threshold, not a guarantee of overall business profit.
Sales your ad platform credits to your campaigns within its attribution window (Amazon and Google Ads default to 7 days of clicks, 14 for views). Attributed revenue is the number to pair with spend from the same platform — mixing numbers from different periods or sources inflates or hides performance.
Yes. The formulas and break-even definition follow Amazon Ads' official ads-math guide, updated September 26, 2025, which is linked in the calculator. Attribution windows are platform settings, so your ad platform's own reporting is the source of the inputs.
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