Core formulas
The formulas to keep straight
ACOS = ad spend / ad-attributed revenue x 100Contribution before ads = ad-attributed revenue - product cost - Amazon fees - shipping - prepBreak-even ACOS = contribution before ads / ad-attributed revenue x 100Target ACOS = (contribution before ads - target profit) / ad-attributed revenue x 100Max ad spend = contribution before ads - target profitROAS = 1 / ACOS as a decimalWhat is break-even ACOS?
Break-even ACOS is the ACOS where ad spend uses every dollar of contribution margin before ads. At that point the campaign has no first-order profit left. If a $100 Amazon sale keeps $35 before ads, break-even ACOS is 35%.
That is the danger line, not the goal. If the seller wants $10 profit from the same $100 sale, max ad spend is $25 and target ACOS is 25%.
A $100 sale with $35 contribution before ads has 35% break-even ACOS.
Break-even ACOS by contribution margin, verified July 4, 2026
Each row uses ad-attributed revenue as the denominator.
| Contribution margin before ads | Break-even ACOS | Target ACOS with 10% profit | ROAS equivalent of target |
|---|---|---|---|
| 20% | 20% | 10% | 10.00x |
| 30% | 30% | 20% | 5.00x |
| 35% | 35% | 25% | 4.00x |
| 40% | 40% | 30% | 3.33x |
| 50% | 50% | 40% | 2.50x |
How do you calculate break-even ACOS?
Calculate contribution before ads first. Subtract product cost, Amazon fees, shipping, prep, packaging, and other order costs from ad-attributed revenue. Then divide that contribution by ad-attributed revenue and multiply by 100.
If ad-attributed revenue is $2,400 and contribution before ads is $960, break-even ACOS is 40%. If the seller wants $240 profit left, target ACOS is 30%.
A $2,400 campaign with $960 contribution before ads has 40% break-even ACOS.
Break-even ACOS formula example
| Line item | Amount | Formula role |
|---|---|---|
| Ad-attributed revenue | $2,400 | Denominator |
| Product cost | $720 | Subtract before ads |
| Amazon fees | $360 | Subtract before ads |
| Shipping and prep | $360 | Subtract before ads |
| Contribution before ads | $960 | $2,400 - $720 - $360 - $360 |
| Break-even ACOS | 40% | $960 / $2,400 |
| Target profit | $240 | 10% of revenue |
| Target ACOS | 30% | ($960 - $240) / $2,400 |
What is the difference between break-even ACOS and target ACOS?
Break-even ACOS leaves zero profit after ads. Target ACOS leaves the profit you chose before the campaign runs. A seller who treats break-even ACOS as the goal is planning to work for no margin on every ad-attributed order.
Use break-even ACOS as the stop line and target ACOS as the operating line. For a mature campaign, target ACOS matters more because it protects cash, refunds, overhead, and restock risk.
A campaign below break-even ACOS can still be too expensive if it misses target ACOS.
Break-even ACOS vs target ACOS
| Metric | What it protects | Best use |
|---|---|---|
| Break-even ACOS | Zero-loss point before overhead | Do not cross without a reason |
| Target ACOS | Profit after ads | Operate profit campaigns here |
| Actual ACOS | Current ad efficiency | Compare with target and break-even |
| ROAS | Same relationship in ratio form | Useful for non-Amazon ad reports |
Can ACOS be higher than break-even?
ACOS can be higher than break-even during a launch, ranking test, keyword discovery period, or clearance push. That spend should be named as a test budget. It is not profit.
A planned test has a cap, a goal, and an end date. Without those, high ACOS becomes a quiet way to turn inventory into revenue without keeping cash.
A launch campaign above break-even ACOS is a marketing cost, not a profitable campaign.
- Use a fixed test budget.
- Separate launch campaigns from profit campaigns.
- Check search term quality, not only ACOS.
- Stop if the campaign cannot explain how it will reach target ACOS.
- Move winners into a profit campaign after the learning period.
Decision table
Break-even ACOS decisions
| Signal | Meaning | Action |
|---|---|---|
| Actual ACOS above break-even | Campaign loses money before overhead | Pause, fix bids, or treat as capped launch spend |
| Actual ACOS below break-even but above target | Some profit remains, not enough | Cap budget and improve conversion |
| Actual ACOS below target | Campaign keeps planned profit | Scale in controlled steps |
| Low ACOS with low sales | Efficient but too narrow | Add search terms carefully |
| High ACOS on thin product | Product cannot fund ads | Fix price, cost, or channel before scaling |
Worked examples
Examples you can compare against your own numbers
Example 1: target ACOS protects profit
An Amazon product earns $100 in attributed sales and keeps $35 before ads.
| Attributed sales | $100.00 | Campaign revenue |
|---|---|---|
| Contribution before ads | $35.00 | After product cost, Amazon fees, shipping, and prep |
| Break-even ACOS | 35% | $35 / $100 |
| Target profit | $10.00 | Profit to keep after ads |
| Target ACOS | 25% | ($35 - $10) / $100 |
Takeaway: The campaign should not be scaled at 34% ACOS if the seller needs $10 profit. It clears break-even but misses target.
Open this break-even ACOS exampleExample 2: a low-looking ACOS still loses money
A thin-margin product spends $260 on $1,000 in attributed sales.
| Attributed sales | $1,000 | Campaign revenue |
|---|---|---|
| Ad spend | $260 | 26% ACOS |
| Contribution before ads | $220 | 22% margin before ads |
| Break-even ACOS | 22% | $220 / $1,000 |
| Profit after ads | -$40 | $220 - $260 |
Takeaway: The campaign loses money even though 26% ACOS may look normal in a report.
Open the losing ACOS exampleAction checklist
Before you use this number in the real business
- 1Use ad-attributed sales and ad spend from the same window.
- 2Subtract product cost, Amazon fees, shipping, prep, and packaging.
- 3Calculate contribution before ads.
- 4Set break-even ACOS from contribution margin.
- 5Subtract target profit to set target ACOS.
- 6Compare actual ACOS with both numbers before scaling.
Common mistakes
Mistakes that make the answer look better than reality
FAQs
Questions people ask before making the decision
What is break-even ACOS?
Break-even ACOS is contribution margin before ads divided by ad-attributed revenue. If a product keeps 35% before ads, break-even ACOS is 35%.
What is a good break-even ACOS?
A higher break-even ACOS means the product has more room for ads. The better operating number is target ACOS, which is lower because it leaves profit after ads.
How do I convert break-even ACOS to ROAS?
Use 1 divided by ACOS as a decimal. A 25% target ACOS equals 4.00x ROAS, and a 40% break-even ACOS equals 2.50x ROAS.
Should my ACOS be below break-even?
Yes for a profit campaign. If ACOS is above break-even, ad spend is larger than contribution margin before ads, so the campaign loses money on first-order economics.
Why is my ACOS profitable on one product and bad on another?
Different products have different costs, Amazon fees, shipping, and contribution margin. The same 30% ACOS can be strong on a 50% margin product and a loss on a 25% margin product.
Sources and notes
Where the assumptions come from
Official Amazon Ads guide defining ACOS, ROAS, break-even ACOS, and target ACOS concepts.
Calculator used for the break-even ACOS and target ACOS examples.
FeeProofed conversion guide for ACOS, ROAS, and profit checks.