Profit per sale after Amazon fees: the math every seller should know

The amount Amazon deposits in your bank is not the profit from the products you sold. A disbursement can include different order periods, refunds, reserves and fees. It also does not subtract the inventory invoice you paid outside Amazon.

To decide whether a product can afford ads or a price promotion, start with one unit's economics. Then reconcile the product totals with the business accounts. This guide uses a hypothetical U.S. FBA product to explain the method. None of its fee figures is a current Amazon rate quote.

Start with the exact product and order

Record the account, marketplace, ASIN, seller SKU and variant. A bottle, a two-pack and a kit can have different costs, dimensions and fees even if they share a parent listing. Use the actual selling price for the period you are reviewing.

Define net product revenue after discounts and expected refunds. Exclude sales tax collected on behalf of tax authorities. Keep shipping revenue and shipping expenses consistent if they apply. Avoid mixing a full list price with the fee and margin of a discounted order.

If a refund is already deducted from revenue, do not deduct that same lost revenue again as a return allowance. You may still need to include separate return processing, disposal or unsellable inventory costs. Write down what the allowance covers so it cannot quietly count twice.

Build a landed product cost

Use the supplier's unit price, then add costs needed to get a sellable unit into your fulfillment process. These may include freight, duty, inspection, labels, preparation and packaging. Allocate shipment costs across a sensible number of units and record the basis.

Keep inbound cost separate if you prefer, but include it exactly once. A supplier quote for goods at the factory is not an all-in product cost. An old invoice for a different bottle size is not an exact match either.

For bundles, include every component and assembly cost. If 100 units were damaged in a shipment, consider how that affects the usable unit cost. Mark estimates as estimates and replace them with actual invoices when available.

Add Amazon and fulfillment costs

Start with the applicable referral fee and fulfillment cost. Review the exact product dimensions, weight, category and fulfillment method in your marketplace. Amazon's fee estimate tools can help you build an initial calculation, but an estimate is not the final charge.

Consider storage and other applicable costs as well. Depending on the product and account, these can include inbound placement, inventory-related charges, returns processing, removals, disposal, coupons and other program costs. Use current account statements and fee schedules to identify which apply.

Spread costs such as storage across the units or period they relate to using a clear rule. A slow-moving product can carry a different storage burden from a fast seller. Check your actual charges rather than copying one fixed allowance across the whole catalog indefinitely.

Amazon's Revenue Calculator walkthrough explains its estimation process. Reconcile those estimates against settlement and transaction records as you accumulate actual sales.

Work through one example

Here is an illustrative unit with $30 of net revenue. All cost figures are invented for the calculation:

The non-ad costs total $19.50. Contribution before ads is $30 − $19.50 = $10.50. If advertising costs $6 per unit sold across the defined product and period, contribution after ads is $4.50 per unit.

That $4.50 still needs to support fixed expenses such as software, insurance, salaries and other overhead. It is useful product contribution, not a claim that the business earned $4.50 of net profit on every order.

Turn contribution into an advertising limit

For an advertised order with the same revenue and product mix, break-even ACOS is contribution before ads divided by net revenue. In the example, $10.50 ÷ $30 = 35%. At that ACOS, an attributed order leaves zero contribution after ads.

If you want $3 left toward overhead and profit, the maximum ad cost for the example order is $7.50. The corresponding target ACOS is $7.50 ÷ $30 = 25%. A lower target may be needed if other costs are still unknown.

Keep ACOS and TACOS separate. ACOS divides ad spend by attributed ad sales. TACOS divides ad spend by total sales for the same scope and period. They answer different questions. Neither percentage alone tells you whether the underlying product margin is adequate.

Do not divide ad spend by total units and call that the acquisition cost of an advertised customer. It is a useful product-period allocation when labeled clearly. Customer acquisition requires a reliable customer definition and appropriate attribution evidence.

Test a price or promotion before approving it

A lower price changes more than revenue. Percentage-based fees, coupon costs, order mix and advertising conversion can also change. Recalculate contribution at the proposed net price and model a range for demand rather than assuming volume will rise enough.

Compare total contribution, not only unit sales. Selling 100 units with $4 left contributes $400. Selling 150 units with $2 left contributes $300. Higher volume can produce less money for the business and require more inventory cash.

Include the timing of deposits, supplier payments and replenishment. A product with healthy contribution can still consume cash while you wait for inventory to arrive and sales proceeds to become available.

Reconcile and keep the inputs current

Maintain one dated cost row per SKU or variant. Record the source invoice, currency, fee evidence and assumptions. Refresh it after supplier changes, packaging changes, fee changes or meaningful shifts in returns and storage.

At month end, compare the product calculations with actual revenue, refunds, fees, ad spend and inventory cost. Explain differences rather than forcing the model to match a bank deposit. Keep unresolved costs visible until the evidence arrives.

Want help finding which missing costs change your decisions? Get a free BrimScout profit audit. We can review your unit economics before recommending more spend.