Formula
Blended ACoS = sum of ad spend ÷ sum of ad-attributed sales × 100
Worked example
Lesson 2 combines Product A’s $8,000 in ad sales and $1,600 spend with Product B’s $2,000 in ad sales and $500 spend. Combined spend is $2,100 on $10,000 in attributed sales, so blended ACoS is 21%. It is not the simple average of their 20% and 25% individual ratios.
Product A has a 40% break-even ACoS and Product B a 20% break-even ACoS. Their simplified contribution after ads is $1,600 and minus $100, respectively. Combined contribution is positive at $1,500, yet Product B still loses money under the model. The account total hides that product-level result.
Why it matters for profit
A blended ratio can summarize an account, but it cannot set a safe target for every product. Compare each product with its own break-even before shifting budget. In this example, the sales-weighted break-even is 36%; comparing 21% with that line describes the combined contribution without making Product B profitable.
Use the same products and cost basis in both the actual and break-even comparisons. This page uses blended ACoS to mean a combination of ad-attributed sales, not ad spend divided by total retail sales; the latter is TACoS. Changes in product mix can move the combined ratio even when each product’s individual performance stays the same.
Check it on your numbers
Use Catalog Profit Check.
Read the worked lesson: Find the products hidden by your blended ACoS.