How to use this calculator
- Enter your ad spend and the ad sales it generated for the same period, for example from your Amazon Ads campaign report.
- Optionally add total sales, ad and organic together, to get TACoS.
- Optionally add your profit margin before ads to see your break-even ACoS and whether your ads make money.
ACoS formula
ACoS = Ad spend ÷ Ad sales × 100
Lower is better: a lower ACoS means you spend less on ads for each unit of sales. Because ACoS and ROAS are reciprocals, ROAS = 1 ÷ ACoS, with ACoS as a decimal.
ACoS to ROAS formula and reference table
The calculator above uses ad spend and sales. Use the formula and table below to look up an ACoS-to-ROAS equivalent.
| ACoS | ROAS |
|---|---|
| 10% | 10.00 |
| 15% | 6.67 |
| 20% | 5.00 |
| 25% | 4.00 |
| 30% | 3.33 |
| 40% | 2.50 |
| 50% | 2.00 |
Working the other way, a ROAS of 3 is an ACoS of about 33.3%. For ROAS-first reporting, use the ROAS calculator.
Break-even ACoS
Your break-even ACoS equals your profit margin before ads. If you keep 30% of each sale after product cost, fees and shipping, you can spend up to 30% of ad sales on ads before you start losing money. Any ACoS below that line is profitable; any ACoS above it loses money on every ad sale.
To get your margin before ads from your actual costs, including marketplace fees and returns, use the break-even ROAS calculator; it shows your break-even ACoS too.
What is TACoS?
TACoS = Ad spend ÷ Total sales × 100
TACoS (total advertising cost of sales) compares ad spend with all your sales, not just the sales ads claim. ACoS tells you how efficient your campaigns are; TACoS tells you how much the business spends relative to its sales. If ad spend stays flat while TACoS falls, total sales have grown. Compare ad-attributed sales on the same basis before attributing that growth to organic sales.
Worked example
You spend $500 on ads that generate $2,000 in ad sales, out of $5,000 in total sales, and your margin before ads is 30%.
- ACoS: $500 ÷ $2,000 = 25%
- ROAS: $2,000 ÷ $500 = 4.00
- TACoS: $500 ÷ $5,000 = 10%
- Break-even ACoS: 30%
- Contribution after ads: $2,000 × 30% − $500 = $100
A 25% ACoS is below the 30% break-even line, leaving a positive contribution before fixed overhead and taxes.
Frequently asked questions
What is ACoS?
ACoS (advertising cost of sales) is the share of ad-attributed sales that you spend on advertising. It is the main efficiency metric in Amazon Ads reports, where it is written ACOS.
How do you calculate ACoS?
ACoS = ad spend ÷ ad sales × 100. If you spend $500 on ads that generate $2,000 in sales, your ACoS is 25%.
How do I convert ACoS to ROAS?
They are reciprocals: ROAS = 1 ÷ ACoS, with ACoS as a decimal. An ACoS of 25% (0.25) equals a ROAS of 4, and a ROAS of 2 equals an ACoS of 50%.
What is a good ACoS?
Any ACoS below your break-even ACoS is profitable, and your break-even ACoS equals your profit margin before ads. A product with a 30% margin loses money above a 30% ACoS, while a product with a 60% margin can afford much more, so there is no universal good ACoS.
What is break-even ACoS?
Break-even ACoS is the ACoS at which ad spend uses up all the profit from ad sales. It equals your margin before ads: selling price minus product cost, fees and shipping, divided by the selling price.
What is TACoS?
TACoS (total advertising cost of sales) divides ad spend by total sales, including organic sales. It shows how dependent the business is on advertising: a falling TACoS with unchanged ad spend means total sales have grown. Compare ad-attributed sales over the same period before drawing conclusions about organic sales.
Why can ACoS be over 100%?
ACoS goes above 100% when ad spend exceeds the sales it generated. Sellers sometimes accept this during a product launch, but it means every attributed sale costs more in ads than it brings in.
By the SellerUtils team · Last updated October 1, 2026. Results are estimates for planning and are not financial advice.