Amazon FBA costs you a referral fee, usually around 15 percent of the sale price, plus a fulfilment fee based on the item's size and weight. Below roughly $12 to $15 a unit, the fulfilment fee often takes more margin than the convenience is worth.
The two main fees
The referral fee is a percentage of the selling price and applies whether you use FBA or ship yourself. Fifteen percent is the most common rate, but categories range from about 8 percent to 45 percent. Look up yours rather than assuming.
The fulfilment fee is what you pay Amazon to pick, pack, ship and handle customer service. It depends on the size tier and weight of your product, so two items at the same price can carry very different fees.
Put your own figures into the Amazon FBA Calculator to see the combined effect on profit per unit.
The costs that surprise people
- Inbound shipping to Amazon's warehouses, which is yours to pay and belongs in your per-unit cost.
- Storage fees, which rise sharply in the final quarter of the year and punish slow-moving stock.
- Long-term storage surcharges on inventory that sits too long.
- Removal or disposal fees when something does not sell.
- Returns processing in categories with high return rates, such as apparel.
Where FBA genuinely wins
Prime eligibility raises conversion, and for many categories that alone justifies the fee. Amazon handles customer service and returns, which is real time back. And you can scale without touching a box, which matters if your constraint is hours rather than capital.
Where FBA loses
Low-priced items, because the fulfilment fee is close to fixed and eats a much larger share of a $10 sale than a $40 one. Oversized or heavy products, where size-tier fees escalate quickly. And slow sellers, where storage costs accumulate quietly month after month.
For those, fulfilling yourself often nets more per unit even after your own time and postage.
Do not forget advertising
Most FBA sellers advertise, and ad spend is a real cost of the sale even though it does not appear on the fee schedule. The number that matters is whether your ACoS sits below your break-even point. We explained that in what ACoS actually means, and the ACoS Calculator works out your break-even figure.
How to decide
Run the numbers per product rather than per business. Most catalogues have some items that are clearly better on FBA and others that clearly are not, and the answer often changes when you raise a price or shrink a box. If you are shipping yourself, check the Dimensional Weight Calculator first, because packaging size may be costing you more than the product weight.