The appeal of FBA is straightforward: your products become Prime-eligible, which dramatically increases conversion rates among Amazon's Prime subscribers, and you remove yourself from the daily operations of picking, packing, and shipping orders. For sellers doing meaningful volume on Amazon, the operational leverage of not managing fulfillment in-house is genuine. Amazon's fulfillment infrastructure is efficient, their Prime shipping is fast, and the Prime badge is one of the most conversion-positive signals available to an Amazon seller.
The cost structure has several components that need to be calculated together to understand the true economics. FBA fulfillment fees cover the picking, packing, and shipping and are charged per unit based on size and weight. A small, lightweight product might cost three to five dollars per unit in fulfillment fees. A larger or heavier product might cost eight to twelve dollars or more. Storage fees are charged per cubic foot per month and increase significantly during the October through December peak period. For slow-moving inventory, storage fees compound and can make FBA economically unsustainable.
Amazon also charges a referral fee on every sale, which is separate from FBA fees. Referral fees range from six percent for electronics to fifteen percent for most general merchandise categories and twenty percent or more for jewelry. When you add the referral fee and the FBA fulfillment fee together, the total Amazon cost on a sale can easily reach twenty-five to thirty-five percent of the sale price before you count your product cost or any marketing spend. Understanding this total cost structure determines whether your product can generate acceptable margins when sold through FBA.
Inventory management for FBA requires more planning than self-fulfillment because the lead time between deciding to send inventory and having it available to sell is typically two to four weeks when you include the time to prepare shipments and Amazon's receiving time at the fulfillment center. Running out of stock on Amazon has significant consequences: your product loses its ranking position during the stockout and takes time to recover after restocking. Conservative inventory management that accounts for this lead time and maintains a buffer against unexpected demand spikes is essential.
The comparison between FBA and self-fulfillment or a third-party logistics provider should be made using actual numbers for your specific products, not general estimates. Build a spreadsheet that models your COGS, your Amazon referral fee, your FBA fulfillment fee, your storage cost based on realistic inventory turns, your advertising spend to maintain visibility, and any prep and shipping costs to send inventory to Amazon. The result tells you whether your specific product economics support FBA or whether a different fulfillment approach would produce better margins.
FBA is the right choice when the conversion uplift from Prime eligibility and the operational leverage of not managing fulfillment produce better net margins than the alternatives, which requires knowing your numbers well enough to make that comparison with confidence.