Amazon FBA economics look simple on the surface and get brutal fast. The referral fee is 15 percent of the selling price in most categories. The fulfillment fee depends on size and weight and can run anywhere from 3 to 15 dollars per unit. Storage fees accrue monthly and spike in Q4. Long-term storage fees kick in after 180 days. Returns processing applies to eligible categories. And none of those are the hidden costs: advertising to stay visible in search, the new inbound placement fee, and the referral fee being charged on shipping revenue. This calculator gives you a quick, honest read on per-unit FBA economics. Enter your selling price, referral fee percentage, FBA fulfillment fee, monthly storage fee, product cost, and units per month — and see referral fees, total FBA fees, net per unit, margin percentage, and monthly profit after all Amazon costs.
Referral Fee per Unit
$5.25
Total Amazon Fees per Unit
$11.50
Net Profit per Unit
$15.50
Margin %
44.29%
Monthly Profit
$46,500
Referral fee per unit is Selling Price multiplied by the Referral Fee Percentage divided by 100. Most Amazon categories charge 15 percent, but grocery charges 8 percent, consumer electronics 8 percent, and jewelry 20 percent — check the current category rate card before trusting the default. Total Amazon fees per unit is the referral fee plus the FBA fulfillment fee plus the FBA storage fee. Net per unit is Selling Price minus Total Amazon Fees minus Product Cost. Margin percentage is Net per Unit divided by Selling Price, expressed as a percentage. Monthly profit is Net per Unit multiplied by Units per Month. This model does not include Amazon PPC advertising spend (which for competitive categories can add 15 to 25 percent of revenue), the inbound placement fee (added in 2024 for sellers who do not split shipments optimally), long-term storage fees (which apply to inventory held over 180 days), or returns processing fees. The true all-in Amazon cost is typically 8 to 12 percentage points higher than what this calculator shows once advertising is included. Use it as the optimistic floor, not the expected case.
Brands that succeed on Amazon FBA typically need a 60 to 70 percent starting gross margin (before FBA fees) just to clear a 15 to 20 percent net margin after the full Amazon tax. A product with a 40 percent pre-FBA gross margin will almost certainly lose money on Amazon once advertising is factored in. The most common failure mode is founders comparing the FBA margin number (before ad spend) to their Shopify direct margin (after everything) and concluding that Amazon is more profitable — it is not. Amazon is a volume channel with a fixed 25 to 35 percent total cost of sale for most mid-market sellers. The right question is not whether Amazon is profitable in isolation, but whether the incremental Amazon volume adds enough contribution to be worth the inventory capital, the operational complexity, and the platform risk. For most DTC brands, Amazon works as a secondary channel at 20 to 35 percent of revenue — rarely as the primary channel.
FBA fees are predictable per-unit economics. The harder margin problem is your non-Amazon channel — the Shopify Plus DTC site where discounting, freight zones, and COGS drift can quietly destroy the margin you are trying to reinvest into Amazon inventory. Agentis does not touch your Amazon listings; it protects the DTC margin that funds them. By enforcing a profit floor on every Shopify Plus checkout order in real time, it ensures the DTC channel delivers the gross profit you budgeted, so you can fund Amazon inventory and advertising without running into a cash wall.
All-in, most mid-market FBA sellers pay 25 to 35 percent of selling price in combined Amazon fees (referral, fulfillment, storage, returns). Categories with large or heavy products can exceed 40 percent. Add 15 to 25 percent for advertising and the true cost of doing business on Amazon is 40 to 60 percent of revenue.
Only for products with high enough starting margins (60 to 70 percent pre-FBA) and defensible pricing power. Commodity products with thin margins almost always lose money on Amazon once advertising is included. Model the math before you scale.
Amazon PPC advertising, inbound placement fees, long-term storage fees (180+ days), and returns processing. Add another 8 to 15 percentage points of revenue to get the realistic all-in cost.
For most mid-market DTC brands, Shopify is the margin channel and Amazon is the volume channel. Shopify margins are typically 10 to 20 points higher per order, but Amazon delivers incremental volume and customer acquisition. Run both with clear contribution margin targets per channel.
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Free profit margin calculator for ecommerce. Calculate gross margin, net margin, and total profit from revenue, COGS, and operating expenses — with benchmark context.
Margin Analysis
The percentage of revenue remaining after subtracting the cost of goods sold — a foundational profitability metric that excludes operating expenses, taxes, and interest.
Margin Analysis
The revenue remaining after deducting all variable costs associated with fulfilling an order — including COGS, shipping, payment processing fees, and pick-and-pack labor.
Cost Management
The total cost of a product delivered to the customer, including COGS, freight, duties, tariffs, insurance, and handling fees.
Total Fee % of Revenue
Side-by-side comparison of total selling fees on Amazon FBA vs Shopify Plus including platform fees, fulfillment, advertising, and payment processing.
Gross Margin %
Industry gross margin benchmarks across 8 major ecommerce verticals — health, beauty, fashion, electronics, home, pet, food, and jewelry.
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