Free Break-Even ACoS Calculator
Enter your sale price and per-unit costs to see your true break-even ACoS — the maximum advertising cost of sale before an ad-driven order stops making money. It also gives you a target ACoS to aim for and the maximum CPC bid your conversion rate can support. Free, no login, all math runs in your browser.
What is break-even ACoS?
Break-even ACoS is the ACoS at which an ad-driven sale makes exactly zero profit — your ad spend per sale equals your profit per sale before ads. Spend a higher ACoS and the sale loses money; spend less and you keep the difference. It is your ceiling, not your target.
Why the 25% rule is wrong
The popular "keep ACoS under 25%" rule ignores your actual COGS, FBA fee, and referral fee. A high-margin product might break even above 50%, while a thin-margin product breaks even at 15%. Optimizing to a generic number means you are either leaving sales on the table or quietly losing money.
How to calculate your break-even ACoS
- Take your sale price.
- Subtract COGS, the FBA fulfillment fee, the referral fee, inbound shipping, and a returns allowance — that is your profit per unit before ads.
- Divide that pre-ad profit by your sale price. The result is your break-even ACoS.
Frequently Asked Questions
- What target ACoS should I aim for?
- Below break-even, by however much profit you want to keep. If you break even at 40% and want to pocket 30% of your margin, your target is about 28%.
- How do I find my max CPC bid?
- Multiply your target ACoS by your sale price and your conversion rate. The tool does this for you.
- Can I automate this?
- Yes. RedHen Labs tracks real profit per product and queues bid changes that hold each product to its own ACoS target — every change waits for your approval, for a flat fee, never a percentage of ad spend. Start a 14-day free trial at rrw-ads.com/pricing.