A fee-only comparison misses the operating tradeoff
FBA bundles pick, pack, shipping, and customer-service responsibilities into Amazon charges. FBM shifts more of those activities to the seller or a logistics partner. Comparing only the visible fulfillment fee leaves labor, packaging, storage, and service costs out of the decision.
Use one common comparison sheet
- Hold selling price, product cost, quantity, advertising, and return assumptions constant.
- For FBA, include fulfillment, storage allocation, inbound placement, preparation, and removal risk where relevant.
- For FBM, include postage, packaging, warehouse labor, software, customer service, and failed-delivery costs.
- Allocate monthly fixed costs across a realistic sales volume instead of an optimistic maximum.
Separate margin from cash timing
An option can produce a stronger operating margin while requiring more cash earlier for inventory or logistics. Review both profit per order and the timing of inventory purchases, carrier invoices, reserves, and settlement deposits.
Recheck when the product changes tiers
Packaging dimensions, shipping weight, storage duration, seasonality, and destination can change the result. Recalculate after packaging changes and before peak periods rather than treating the first comparison as permanent.