ACoS (Advertising Cost of Sales)
ACoS (Advertising Cost of Sales) is ad spend divided by ad sales — the percentage of your advertising revenue that went back out the door as advertising cost. Spend $500 on a campaign that generates $2,000 in ad-attributed sales, and your ACoS is 25%: twenty-five cents of ad cost per dollar of ad revenue.
What is ACoS?
ACoS (Advertising Cost of Sales) is ad spend divided by ad sales — the percentage of your advertising revenue that went back out the door as advertising cost. Spend $500 on a campaign that generates $2,000 in ad-attributed sales, and your ACoS is 25%: twenty-five cents of ad cost per dollar of ad revenue.
It’s the standard efficiency gauge of Amazon PPC — the number campaign managers live in. But it measures the campaign, not the business: it knows nothing of your COGS, fulfilment costs, or margins. ACoS answers “is this campaign efficient?”; whether it’s profitable is a different number (break-even ACoS) and a different question.
How to calculate it — and its cousin ROAS
Two mirrors of the same truth:
Break-even ACoS: the only target that matters
Your break-even ACoS is the spend level at which a paid sale contributes exactly zero profit. Sale price $100, all-in pre-ad profit $35 — break-even ACoS is 35%. Above it, every paid sale costs you money; below it, every paid sale pays you. “Good ACoS” isn’t 15% or 25% — it’s any number deliberately placed relative to your break-even: below it to harvest profit, at it to buy velocity and rank during launches.
Why ACoS is not profitability
A 40% ACoS on a 60%-margin product is a money printer; a 15% ACoS on a 12%-margin product is a slow leak. Sellers who chase a universal ACoS benchmark scale revenue while shrinking profit — the dashboard celebrates, the bank balance disagrees. Anchor every campaign target to that product’s break-even, and recompute it whenever fees or costs move.
Fulfilment quietly moves your ACoS
FBA’s Prime badge converts better, and conversion is the denominator of click efficiency — so FBA listings often run lower ACoS on identical keywords. FBM sellers compensate with differentiated products and stronger listings, or accept paying more per sale for the same traffic. When you benchmark ACoS against competitors, compare within your fulfilment model, not across.
ACoS vs TACoS
ACoS measures the paid channel alone. TACoS — ad spend against total sales, organic included — measures whether ads are building the business. New launches run high ACoS by design (buying velocity); success looks like TACoS falling over time as organic rank takes the load. If ACoS is healthy but TACoS never improves, your ads are renting sales, not building them.
In practice
A bamboo cutting-board set launches with a 20% ACoS target against a 45% gross margin — comfortably under break-even. Every paid sale banks profit while the velocity pushes the main keyword up the organic page. By month three, organic orders carry most of the volume; the campaigns keep running at the same ACoS, but on a shrinking share of total sales. That’s the machine working.
How Harpy Media helps
We manage PPC to margin, not to vanity benchmarks — break-even ACoS computed per SKU, campaigns layered for launch, profit, and defense. It’s the difference between ads that report well and ads that pay.
ACoS FAQ
How do I lower my ACoS?
Negate non-converting search terms, shift spend from broad to exact-match, and improve conversion (images, copy, price) — fewer wasted clicks per sale.
What is a good ACoS on Amazon?
Any ACoS deliberately placed relative to that product’s break-even. Many categories run 15–25% in steady state, but a 30% launch ACoS buying rank can be right, and a 12% ACoS on thin margin can be wrong.
What is the difference between ACoS and TACoS?
ACoS = ad spend ÷ ad sales (channel efficiency). TACoS = ad spend ÷ total sales — the business-level view of whether ads are building organic momentum.
How do I calculate break-even ACoS?
(Sale price − COGS − Amazon fees − fulfilment) ÷ sale price × 100. At or below it you’re buying rank; above it you’re buying losses.
Related terms
CPS (Cost per Sale)TACoS (Total Advertising Cost of Sales)ROAS (Return on Ad Spend)CPPU (Cost per Purchased Unit)Want these numbers watched for you, every week?
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