Amazon’s headline referral rate (often around 15% by category) is the number people quote. Operators care about contribution after referral + FBA + storage share + expected returns.
The cost layers
| Layer | What it is | Why it matters |
|---|---|---|
| Referral | % of item price (category-based) | Scales with price |
| FBA fulfillment | Pick, pack, ship by size/weight tier | Can exceed referral on small cheap items |
| Storage | Monthly, peak season higher | Kills slow inventory |
| Returns / refund admin | Lost product + fee patterns | Must be assumed, not hoped away |
| Ads (optional) | Sponsored products etc. | Customer acquisition, not “Amazon fee,” but real |
Sketch: $28 item, 15% referral, $5.20 FBA, $11 product
Referral $4.20 + FBA $5.20 = $9.40 platform-side before storage and ads.
$28 − $9.40 − $11 product = $7.60 before storage, returns, and PPC. That $7.60 is not “salary.”
If FBA were $7.50 on a bulkier unit, contribution collapses fast. Size your packaging as carefully as your ad bid.
FBM vs FBA in one sentence
FBM keeps fulfillment under your control and can protect margin if you ship cheaply. FBA buys Prime eligibility and ops leverage at a clear per-unit cost. Neither is “cheaper” without your numbers.
Import sellers
If goods come from overseas, platform fees sit on top of landed cost (product + freight + duties + last-mile). Margin math that ignores landed cost is fiction.