Key takeaways: Build profit per unit for every ASIN from selling price, referral fee, FBA fee, landed cost, returns, promotions and storage. The result gives you break-even ACoS, the ceiling for advertising on that product, and tells you which ASINs to scale, hold, fix or retire. Most accounts find the margin leak is not where they assumed.
Why the average margin is useless
An account with 35% blended margin can contain a best-seller at 48% and a slow variation at 9%, and the ad budget usually flows to whichever sells most units, not whichever earns most profit. Growth funded by the 9% product does not pay for itself. Growth funded by the 48% product does. You cannot see which is which until the margin is built per ASIN, and per child where variations have different costs.
The build, line by line
Start with the selling price and subtract in this order:
| Line | Where to find it | Notes |
|---|---|---|
| Referral fee | Fee preview in Manage Inventory, or the Payments report | Percentage of price by category; most categories sit around 15% but check yours |
| FBA fulfillment fee | Fee preview, Revenue Calculator | Set by size tier and weight; small changes in packaging can move the tier |
| Landed cost | Your own records | Unit cost plus inbound freight, duty and prep, divided per unit |
| Storage | Monthly Storage Fees report | Monthly and, if applicable, aged-inventory surcharges, allocated per unit sold |
| Returns | FBA Returns report | Refund cost plus the share of returns not resold, as a percentage of units |
| Promotions | Promotions and coupon reports | Coupon redemptions, deal fees, Subscribe & Save discounts averaged per unit |
| Inbound placement | Shipment summaries | Placement service fees where they apply to your inbound configuration |
What remains is margin before advertising. Divide it by the selling price and you have break-even ACoS: the ACoS at which advertising exactly consumes the profit on an ad-attributed sale. A product with $8 margin on a $25 price has a break-even ACoS of 32%. Anything above that on that ASIN loses money on every paid order, whatever the organic sales look like.
From break-even to a target
Break-even is a ceiling, not a target. The target ACoS depends on what the ASIN is for. A launch can run at or above break-even for eight to twelve weeks because it is buying rank and reviews. A mature product should run well under break-even so paid orders contribute profit and the organic orders add to it. A product being retired should run only defensive branded terms or nothing. That lifecycle logic is what C9 · Where each product is in its lifecycle in our playbook sets targets from, and it is why one account-wide ACoS target is nearly always wrong.
Scale, hold, fix or retire
Read this flowchart as text
- Profit per unit built for every child ASIN
- Margin before ads above 30%?
- Conversion and rank healthy?
- Scale: more budget, more terms, stock check first
- Fix the page, then scale
- Leak identifiable: fees, returns, promos?
- Fix the leak: packaging, price, promo mix
- Retire or reprice; defensive ads only
- Profit per ASIN rising, growth self-funded
With the table built, every ASIN falls into one of four calls. Scale the ones with strong margin and a healthy page: they can fund more spend and more keywords. Fix the ones with strong margin but weak conversion or rank: the profit is there, the page is holding it back. Fix the leak on the ones with thin margin and an identifiable cause: a size tier that a packaging change could drop, a return rate driven by a sizing gap in the images, a coupon that never switched off. Retire or reprice the ones with thin margin and no fixable cause; keep them alive for catalog completeness if they help the parent, but stop advertising them.
The leaks we find most often
The FBA fee tier is the first. A product a few millimeters or a few grams over a tier boundary pays the next tier's fee on every unit. The return rate is the second, and it is usually an expectation gap: the images or bullets promise something the product does not deliver, and the FBA returns report will tell you the reason codes. The third is promotions that outlived their purpose: a launch coupon still running a year later, or a Subscribe & Save discount on a product no one reorders.
Keep it current
Fees change, usually announced with notice and effective early in the year, with storage and other surcharges changing seasonally. Rebuild the table whenever Amazon publishes a fee update, whenever your landed cost moves, and at least quarterly regardless. An ACoS target set on last year's fees can be quietly below break-even today.
Frequently asked questions
What is a good profit margin on Amazon?
After all Amazon fees and before advertising, many sustainable private-label products sit between 25% and 40%. Below about 20% there is little room for advertising at all, and the product needs a price or cost change before it can grow.
How do I calculate break-even ACoS?
Divide margin before advertising by selling price. If a $30 product has $9 left after referral fee, FBA fee, landed cost, returns and promotions, break-even ACoS is 30%.
How often should I rebuild the profit table?
Whenever Amazon publishes a fee change, whenever your landed cost or price moves, and at least once a quarter regardless. An ACoS target set on last year's fees can be quietly below break-even today.
Should I stop advertising products with thin margins?
Stop growth advertising on them. Keep branded and defensive terms if the product protects a parent listing or a customer relationship, and work on the leak that made the margin thin before deciding to retire it.