ACoS (advertising cost of sale)
Reviewed by Akhil Suresh Nair, updated
ACoS, advertising cost of sale, is what you spent on ads divided by the sales those ads brought in, shown as a percentage. Amazon Ads calculates it as (ad spend ÷ ad revenue) × 100, so $50 of spend that earns $100 in attributed sales is an ACoS of 50%. Amazon uses it to measure pay-per-click campaigns such as Sponsored Products.
Why it matters for CPG brands
ACoS answers one narrow question: did this campaign earn back what it cost? Amazon Ads says there's no definitive good ACoS, because it depends on your industry, company size and how often you run campaigns. What it does tie the number to is margin. To stay profitable, ACoS has to sit below your profit margin, and that line is your break-even ACoS. It only counts ad-attributed sales, so pair it with TACoS to see how much the whole product leans on ads. Amazon also points out that new campaigns tend to start with a high ACoS just because they're new.
Example
Say a granola brand keeps 30% of each sale after product cost, fees and shipping, so its break-even ACoS is 30%. A Sponsored Products campaign spends $600 and drives $2,400 in attributed sales. That's an ACoS of 25%, so the ads pay for themselves on those sales, and the ROAS is 4. If the granola sells $8,000 in total that month, TACoS is 7.5%. (These are example numbers, not a client result.)
Read more
- Unified Marketplace Data: Why Amazon, Walmart and Shopify Brands Need One Source of Truth
- Amazon's ad business made $68.6 billion in 2025
- Walmart sells $150B online. Its ads are growing faster
Related XENA products
- XENA 360: Unified marketplace sales, ads and operations
Frequently asked questions
Answers are drawn from the sources listed at the end of this page.
How do you calculate ACoS?
Divide ad spend by the sales the ads drove, then multiply by 100. In Amazon Ads' own example, $50 spent and $100 earned is an ACoS of 50%.
What's the difference between ACoS and ROAS?
They use the same two numbers, flipped. ROAS is ad revenue divided by ad spend, so an ACoS of 50% is a ROAS of 2.
What is a good ACoS on Amazon?
Amazon Ads says there's no definitive number. Start from break-even ACoS, which is your profit margin: below it, the ads earn more than they cost on the sales they drive. Your target then depends on whether the goal is profit, sales growth or brand awareness.
What's the difference between ACoS and TACoS?
ACoS divides ad spend by ad-attributed sales. TACoS divides the same spend by total sales, ad and organic. ACoS judges a campaign; TACoS shows how dependent the product is on advertising.
Related terms
Sources
Third-party facts are from the linked pages, checked Oct 27, 2026. Examples are illustrative unless they link to a published XENA case study.