Amazon FBA Fees and Contribution Margin: A Practical Model
FBA referral, fulfillment, and storage fees turn Amazon revenue into a different economics game. How to compute contribution margin sellers can trust.
Amazon FBA contribution margin is net proceeds after referral fees, fulfillment fees, storage, returns processing, and ads—not the “profit” estimate in a single Seller Central widget.
Fee stack
Referral fee, FBA pick/pack/weight, monthly/long-term storage, inbound placement, refund administration, and Sponsored Products when you treat ads as variable.
In CostRadar, Seller Central Finances events roll into orders.allocated_costs / net_profit, with FeeType rows (Commission, FBAPerUnitFulfillmentFee, …) on order expand and Settlements reconcile for payout windows. Storage is still often manual. Amazon Ads → ASIN ACoS/TACoS product path is shipped (OAuth + Campaign Profit / ASIN APIs); merchant Connect / live spend waits Amazon Ads Partner Network approval.
Seasonal storage and oversized fees can flip a hero SKU negative overnight.
Model template
Start from item price − promotions. Subtract COGS and the fee stack. Subtract attributed PPC. What remains is contribution before corporate overhead.
Re-run the model when Amazon changes fee schedules—annual “fee updates” are material events.
FAQ
Is FBA or FBM more profitable?
It depends on size, velocity, and your warehouse cost. Compare contribution margin, not convenience alone.
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CostRadar connects Amazon alongside Shopify, Woo, and BigCommerce so FBA fee reality (order net + FeeType lines + Settlements + Reimbursements detect/track) sits in the same profitability OS.