Amazon makes it easy to see revenue.
Every sale shows up quickly, and a product that sells well can feel like a success from the first week.
But revenue is not profit.
Between the price a customer pays and the money a seller actually keeps, there is a long list of costs: Amazon's own fees, fulfillment, storage, inbound shipping, advertising, returns and, for many sellers, import costs and currency movements.
A product can sell every day and still earn very little. In some cases, it can lose money on every unit.
That is why the useful question is not:
“Does this product sell?”
It is:
“Do the economics still make sense once every cost of the sale is included?”
The basic Amazon margin calculation, and why it is incomplete
Many sellers start with a simple calculation:
Selling price − product cost = apparent profit
If a product costs $10 from the supplier and sells for $40 on Amazon, the apparent profit is $30, or a 75% margin.
That number is useful as a first filter. It tells you whether there is room to work with.
But it is not the profit margin of an Amazon sale. It leaves out almost everything that happens between the supplier and the customer, and many of those costs only appear once the product is live, the ads are running and the first returns come back.
Costs Amazon sellers should consider
Not every cost applies to every seller. The point is to check each one deliberately rather than discover it later.
Product and supplier cost
The price you pay the supplier per unit. If you buy in a different currency, this also depends on the exchange rate you actually pay.
Amazon referral fees
Amazon charges a referral fee on most sales, usually calculated as a percentage of the selling price. The rate depends on the marketplace and the product category, and some categories also have a minimum fee per item.
FBA fulfillment fees
If you use Fulfillment by Amazon, Amazon charges a fee to pick, pack and ship each order. It depends on the product's size and weight, the marketplace and the program, and Amazon updates its fee schedules from time to time.
Storage-related costs
Inventory held in Amazon's fulfillment centers incurs storage fees, which can vary by season, product size and how long the stock sits. Slow-moving or excess inventory can add further charges.
Inbound shipping and freight
Getting stock from your supplier, or your own warehouse, into Amazon's network costs money. That includes freight, local delivery and any handling along the way.
Packaging and prep
Labels, polybags, bubble wrap, boxes and any prep work required before stock is accepted all add cost per unit.
Advertising
For many products, Amazon Ads are a significant part of the cost of each sale. More on this below.
Returns and refunds
Some customers will return what they buy. Depending on the product and the reason, you may lose the fees on that sale, pay for return processing, or be left with stock that cannot be resold.
Payment and other marketplace costs
Depending on how and where you sell, there may be other fees tied to the transaction, such as program fees, closing fees in some categories, or currency conversion charges on payouts.
Duties and import costs
If you source internationally, customs duty, brokerage and other import charges are part of what the product really costs before it reaches Amazon.
Taxes that are a genuine cost
VAT, GST or sales tax collected from the customer and passed on to the tax authority is usually not profit, but it is not always a cost to you either. Where tax is recoverable, it generally passes through. Where a tax cost cannot be recovered in your situation, it does reduce what you keep, and it belongs in the calculation. The right treatment depends on your registration and circumstances, so it is worth confirming with a tax adviser.
Currency and FX exposure
If you buy in one currency and sell in another, the exchange rate affects your margin. A rate that moves against you between ordering and selling can change the result of a product you thought was safe.
Other costs directly tied to the sale
Anything else that scales with each unit sold: inserts, warranties, software charged per order, or a commission to a partner.
Amazon's fees vary by marketplace, category, fulfillment method, product size and weight, program and time. That is why this article does not list fee rates. Always check the current figures for your own product in your Amazon Seller Central account or Amazon's published fee pages before relying on them.
A more realistic Amazon profit formula
A fuller view of a single sale looks something like this:
Real profit = Selling price − product cost − Amazon fees − fulfillment and shipping − advertising − returns − import and non-recoverable tax costs − other relevant costs
Real margin % = Real profit ÷ Selling price × 100
This is a way of thinking about the economics of a product, not a universal accounting rule. Which costs apply, and how they should be treated, depends on your marketplace, your fulfillment method, where you source from and your tax position.
The goal is simply to make sure nothing that genuinely reduces your profit is left out. For a step-by-step approach that applies beyond Amazon, see how to calculate true profit margin before selling.
An illustrative example
The figures below are invented for illustration only. They are not Amazon's current fees and do not represent any real product or marketplace.
A seller is considering a product that sells for $40 (before any VAT or sales tax) and costs $10 from the supplier.
Apparent profit: $40 − $10 = $30, a 75% margin.
Now the seller lists the full cost of each sale. All figures are illustrative:
- Supplier cost: $10.00
- Referral fee: $6.00
- FBA fulfillment fee: $5.50
- Storage, allocated per unit: $0.50
- Inbound freight: $1.50
- Import duty: $1.00
- Packaging and prep: $0.75
- Advertising, per unit sold: $6.00
- Returns allowance: $1.25
Total cost per unit: $32.50
Real profit: $40 − $32.50 = $7.50, an 18.75% margin.
The product is still profitable in this example. But the margin is about a quarter of what the first calculation suggested.
That difference changes decisions. At 75%, a seller might happily cut the price, increase ad spend or accept a higher supplier quote. At 18.75%, each of those moves needs to be checked first, because there is far less room before the product stops making money.
Why advertising matters so much
Advertising is often the cost that moves an Amazon margin the most, and it is the easiest one to underestimate.
When ads increase sales, revenue grows. But if each additional sale carries a high advertising cost, profit may grow much more slowly than revenue, or not at all.
A few points worth keeping in mind:
- Advertising is a real cost of the sale, so it belongs in the margin calculation, not just in a separate marketing budget.
- Launch periods often need heavier ad spend than a product will need later. A launch margin and a steady-state margin can look very different.
- Ad costs can change with competition, season and keyword prices, often outside your control.
There is no single advertising cost ratio that is right for every product. The level a product can sustain depends on its price, its other costs and the margin you need to make. The useful question is not “What ACOS should I aim for?” in general, but:
“How much advertising cost per unit can this product carry before it falls below my target margin?”
FBA vs merchant-fulfilled economics
With Fulfillment by Amazon, Amazon stores, picks, packs and ships your orders, and charges fulfillment and storage fees for doing so.
With merchant fulfillment, you handle storage and shipping yourself or through a third-party logistics provider. You avoid FBA's fees, but you take on your own warehousing, packaging, labor and carrier costs, and possibly different delivery expectations.
Neither model is universally better. The cost structure is different, and so is the effect on sales and customer experience. The right comparison is to model the full cost per unit under each option for your specific product, rather than comparing one fee in isolation.
International sourcing and landed cost
For many Amazon sellers, the product is manufactured abroad. That adds a layer of cost before any inventory reaches Amazon:
- Freight: sea, air or rail transport, plus local delivery at each end.
- Customs and duties: duty rates depend on the product, its origin and the destination market, and are usually calculated on a customs value rather than the selling price.
- FX: the supplier may invoice in a different currency, so the cost in your selling currency depends on the exchange rate.
- Incoterms: the agreed Incoterm determines which of these costs and responsibilities sit with you and which sit with the supplier. It does not set the costs themselves.
The supplier quote is only the starting point. What matters for margin is the landed cost: what the product really costs once it has arrived and is ready to sell.
Stress-testing an Amazon product before committing
A margin calculated with today's numbers is a snapshot. Before ordering inventory, it is worth asking what happens if those numbers move:
- What if advertising costs per unit increase?
- What if the supplier raises its price?
- What if freight becomes more expensive?
- What if returns increase?
- What selling price would I need to keep my target margin?
MarginGuides is built to answer questions like these before you commit.
You enter your own figures for the product, including the Amazon fees and costs that apply to it. MarginGuides does not connect to Amazon or look up Amazon fees for you, so the numbers are the ones you supply. Analyze then shows the real profit and margin, the break-even price and, if you set a target margin, the selling price needed to reach it. If returns are a concern, you can run the analysis again with a higher return rate and compare.
Stress Test applies an explicit change, such as a higher supplier cost, higher advertising cost, higher fees or a different exchange rate, and shows how profit, margin and the decision change.
Resilience runs several adverse changes against the same baseline and shows which one would cost the most profit. It compares only the changes you choose; it does not forecast or estimate how likely they are.
Improve My Margin works backwards from your target margin. For example, it can solve for the maximum marketing and acquisition cost per unit the product can carry before it falls below target, or how far the supplier cost would need to fall to reach it.
Excel vs a decision engine
A well-built spreadsheet can model all of this. Many Amazon sellers already track their product economics in Excel or Google Sheets, and do it well.
The challenge usually grows with the number of products, markets and what-if questions: each scenario becomes another copy of a sheet to build, check and keep in sync.
MarginGuides is designed to make that scenario testing more structured, with the same calculation behind every analysis and every stress test. For a fuller, balanced comparison, see MarginGuides vs Excel.
Conclusion
A product should not be judged only by whether it sells.
It should be judged by whether the economics still make sense once the full cost structure is included: Amazon's fees, fulfillment, storage, shipping, advertising, returns, import costs and currency.
Doing that work before ordering inventory is much cheaper than discovering a thin margin after the stock has arrived.