FBA profit is thinner than the sale price suggests.

Amazon FBA charges a referral fee on the sale, a separate fulfillment fee based on size and weight, and storage fees that vary by season and how long inventory sits. Add your own product cost and ad spend, and the margin on a listing is often much thinner than the price tag implies.

Referral fee is category-dependent

The referral fee is a percentage of sale price that varies by product category, often with a minimum fee floor for low-priced items. Two products at the same price in different categories can carry meaningfully different referral rates.

FBA fulfillment fees scale with size and weight, not price

Fulfillment fees are based on product dimensions and weight tier, not sale price. A large, light item (think a big but cheap plastic product) can carry a disproportionately high fulfillment fee relative to its price.

Storage fees punish slow movers

Monthly storage fees are charged per cubic foot and increase substantially in Q4 (October-December). Inventory sitting longer than 365 days can incur additional long-term storage surcharges. Slow-moving, bulky SKUs are the most exposed to this cost.

Find your real break-even price

Break-even sale price = the price at which referral fee, fulfillment fee, storage, product cost and ad spend exactly consume your revenue. Pricing below that, even briefly for a promotion, means every unit sold loses money — know that number before you run one.