ACoS (Advertising Cost of Sales)

ACoS, or Advertising Cost of Sales, is the percentage of ad-attributed revenue that was spent on Amazon advertising to generate that revenue. It is the primary efficiency metric for Sponsored Products, Sponsored Brands, and Sponsored Display, calculated per campaign, ad group, or keyword.

Why It Matters for Sellers

ACoS is the single number that tells you whether a campaign is profitable. When ACoS is below your break-even (the point where ad spend equals product margin), the campaign is making money on every incremental sale; when it is above, the campaign is losing money on ads even if the top-line looks healthy. Sellers who scale ad spend without watching ACoS routinely grow revenue while shrinking profit — a common trap in the first six months of running Amazon PPC.

How It Works

  1. Amazon tracks every click on your ad and every purchase of the advertised ASIN within the 7-day (Sponsored Products) or 14-day (Sponsored Brands) attribution window.
  2. Ad spend is summed across the campaign, ad group, or keyword.
  3. Ad-attributed revenue is summed the same way.
  4. ACoS is computed as ad spend divided by ad revenue, multiplied by 100.
  5. Amazon displays ACoS in the Campaign Manager alongside impressions, clicks, CTR, CPC, and orders.

Formula and Worked Example

  • Formula: ACoS = (Ad Spend ÷ Ad Revenue) × 100
  • Break-even ACoS = your product’s gross margin as a percentage of price.

Worked example: A product sells for $40 with $18 of margin after COGS, referral fee, and fulfillment. Break-even ACoS = $18 / $40 = 45%.

If a campaign spent $600 last month and drove $2,000 in ad-attributed sales, ACoS = $600 / $2,000 = 30%. That is 15 points below break-even, so every dollar of ad spend produces roughly $0.33 of incremental profit — a strong campaign worth scaling.

If the same campaign spent $600 and drove only $1,000 in ad-attributed sales, ACoS = 60%, well above the 45% break-even. That campaign is destroying margin on every ad sale and needs bid cuts, negative keywords, or a listing conversion fix.

FAQ

What is a good ACoS on Amazon?

A good ACoS is any ACoS below your break-even, which is set by your product margin. For most private-label sellers, break-even lands between 25% and 45%, so target ACoS is usually 15-30%.

What is the difference between ACoS and TACoS?

ACoS uses only ad-attributed revenue in the denominator; TACoS (Total ACoS) uses total revenue (ads + organic). TACoS reveals whether ads are helping the ASIN as a whole — a falling TACoS while ACoS holds steady means organic sales are growing.

What is the difference between ACoS and ROAS?

ROAS (Return on Ad Spend) is the inverse of ACoS: ROAS = Ad Revenue ÷ Ad Spend. An ACoS of 25% equals a ROAS of 4.0. Both measure the same thing; use whichever your team is more fluent in.

Should new-launch campaigns have low or high ACoS?

High. During launch, the goal is sales velocity to build reviews and organic rank, so most sellers intentionally run above break-even for 30-90 days, then compress ACoS once organic sales carry the ASIN.

How SellerSonar Helps

  • Keyword Monitoring tracks the organic rank of every keyword you also bid on, so you can pull PPC spend when organic rank is strong enough to carry the sale.
  • The PPC Strategies guide covers how to structure campaigns around ACoS targets by product lifecycle stage.
  • Watch organic rank and ad-driven sales in one place to see whether ads are lifting the whole ASIN or just cannibalizing organic clicks.

Start a free 14-day trial and see how your PPC keywords are ranking organically in under 5 minutes.

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