How to calculate margin and profitability on Amazon

You calculate a product's real profitability on Amazon from the gross price the customer pays, subtracting in turn: VAT, the Amazon referral fee, the fulfilment fee (FBA), the cost of goods (COGS), freight to the Amazon warehouse, storage, advertising (PPC) and a reserve for returns. What is left is the net profit per unit. Divided by net revenue (excluding VAT), it gives the net margin as a percentage. That number, not the simple gap between price and cost of goods, tells you whether a product earns.

Below you get a repeatable formula, a cost checklist and a full worked example for a single product. The specific referral and FBA rates differ between categories and countries and change over time, so the example uses illustrative values and points you to the article on Amazon and FBA fees and the FBA calculator in Seller Central for current figures.

The price-to-profit formula (cost checklist)

Always work in net amounts (excluding VAT). The order:

1. Gross selling price is the amount the customer pays (it includes VAT).
2. Minus VAT gives net revenue. For a VAT-registered business this is not a cost: you collect VAT from the customer and remit it to the tax office, and you deduct the input VAT on your costs. You subtract it only so you can calculate margin on net amounts. Germany's standard rate is 19%, but it depends on the product category and country of sale (as of 2026).
3. Minus the Amazon referral fee, charged as a percentage of the price. Important: Amazon calculates the referral fee on the full price the buyer pays, including VAT and shipping (sell.amazon.de, pricing), so do not calculate the referral amount from the net price.
4. Minus the fulfilment fee (FBA fulfilment fee), which depends on weight and size, if you sell in the Amazon FBA model.
5. Minus the cost of goods (COGS), that is the purchase or production price plus duty and freight to you, per unit.
6. Minus inbound logistics to Amazon, that is freight to the warehouse, per unit.
7. Minus storage, averaged per unit, accounting for the season and for slow-moving stock.
8. Minus advertising (PPC), that is campaign spend per unit sold.
9. Minus a returns reserve, that is the statistical cost of returns and goods that cannot be resold.

What is left is the net profit per unit. Where items 3 and 4 come from is explained in the separate article on Amazon and FBA fees.

Gross margin vs net margin: why they are not the same

This is the most common source of illusion. Two different numbers describe two different things.

Gross margin looks only at the price and the cost of goods:

Gross margin % = (net revenue − COGS) / net revenue × 100

Net margin looks at what really stays in your pocket after all costs:

Net margin % = net profit per unit / net revenue × 100

A product can have a gross margin of 70% and a net margin below 20%, because the referral fee, FBA, advertising and returns eat the difference. You make the "sell it or not" decision on net margin. Gross margin only tells you how much room you have for all those costs.

A worked example, step by step

Take one product: an LED desk lamp sold in the FBA model. All the rates below are illustrative and serve to show the method, they are not a current Amazon price list. For real values, use the FBA calculator in Seller Central and the article on Amazon and FBA fees.

Inputs (example):

• Gross selling price: 49.00 EUR (incl. 19% VAT)
• Amazon referral fee: 15% (illustrative)
• FBA fulfilment fee: 4.50 EUR (illustrative)
• COGS delivered to you: 12.00 EUR
• Freight to the Amazon warehouse: 1.20 EUR / unit
• Storage (averaged): 0.60 EUR / unit
• PPC advertising (averaged per unit sold): 4.00 EUR
• Returns reserve: 1.20 EUR / unit

The calculation:

Results for this example:

• Net profit per unit: 10.33 EUR
• Net margin: 10.33 / 41.18 = 25.1%
• Gross margin (price − COGS only): (41.18 − 12.00) / 41.18 = 70.9%

The contrast between 70.9% and 25.1% is the whole lesson. If this seller looked only at gross margin, they would be convinced the product was highly profitable. In reality, a quarter of net revenue is left, before income tax and the cost of their own work.

ROI, ROAS and break-even ACoS: when advertising starts eating profit

Margin tells you how much is left from one sale. Three further metrics tell you how efficiently your capital and advertising work.

ROI (return on invested capital) relates profit to the money tied up in the product:

ROI % = net profit / capital committed × 100

In the example, measured against the cost of goods (12.00 EUR), ROI is 10.33 / 12.00 = 86%. If you add freight and fees paid up front to the committed capital, ROI is lower. So always state what you include in the denominator.

ROAS and ACoS describe the same thing from two sides. ROAS is advertising revenue divided by advertising spend, and ACoS (Advertising Cost of Sale) is advertising spend divided by advertising revenue. They are each other's inverse: an ACoS of 10% is a ROAS of 10.

Break-even ACoS is the threshold above which advertising stops earning. It equals your profit margin measured before the advertising cost (an industry definition, e.g. Ad Badger):

Break-even ACoS % = profit before ads / net revenue × 100

In the example, profit before ads (before subtracting the 4.00 EUR of PPC) is 14.33 EUR, that is 14.33 / 41.18 = 34.8%. It means that as long as advertising spend per sale does not exceed about 35% of net revenue (roughly 14 EUR), the sale still earns. Our actual PPC is 4.00 EUR, an ACoS of about 9.7%, well below the threshold. As ACoS approaches break-even, profit melts to zero; above it, you lose money on every sale.

A metric worth tracking alongside ACoS is TACoS (total ACoS), that is total advertising spend divided by total revenue, including organic sales. It shows how dependent the whole product is on advertising.

The most common mistakes in profitability calculations

• Skipping VAT, or calculating margin on gross amounts. Margin is calculated net. Mixing gross and net can inflate the margin by a dozen or more percentage points.
• Calculating the referral fee from the net price. Amazon charges the referral fee on the price the customer pays, with VAT and shipping, so the referral amount is higher than it looks from the net price.
• Forgotten storage and aged-stock fees. Storage can be invisible with fast turnover and painfully visible with slow turnover and in the season, when rates rise.
• No returns reserve. In some categories, returns run from a few to over ten percent, and returned goods do not always go back on sale.
• Ignoring the cost of capital and the cash cycle. Money is tied up in goods and in transit, while Amazon's payouts arrive with a delay. When you finance inventory, there is a real interest cost that the per-unit margin does not show.
• Setting a price with no link to the Buy Box. Too aggressive a price cuts margin; too high a price loses the Buy Box and the sales. Price is optimised together with margin, not in isolation from it.

If you want these numbers calculated properly, once, for the whole catalogue, that is what our marketplace account management is for.

FAQ

Is VAT a cost that reduces margin?

For a VAT-registered business, VAT is not a product cost. You collect it from the customer and remit it, and you deduct the input VAT on purchases and fees. You subtract it from the gross price only to calculate margin on net amounts. It is different for a seller exempt from VAT, for whom input VAT genuinely raises the cost.

On what price does Amazon calculate the referral fee?

On the full price the buyer pays, including VAT and shipping, not on the net price. That is why the referral amount is calculated from the gross price (sell.amazon.de, pricing).

What net margin on Amazon is "good"?

There is no single number. It depends on the category, turnover, cost of capital and whether the product builds a brand or only volume. Rather than aiming at an abstract percentage, compare net margin with break-even ACoS and with ROI. We do not promise specific results, because they depend on the product and the market.

How does ROAS differ from ACoS?

They are inverses. ACoS is advertising's share of advertising revenue; ROAS is how much revenue one euro of advertising brings. An ACoS of 20% corresponds to a ROAS of 5.

Summary

A product's profitability on Amazon is the net profit after all costs, not the gap between price and cost of goods. Run the price-to-profit formula for every product, look at net margin, ROI and break-even ACoS together, and do not skip VAT, storage, returns or the cost of capital.

At Amazonway we calculate this profitability for the whole catalogue during WP 01 (Direction) of the Waypoint framework, that is the account and margin audit at the start of an engagement. It shows which products actually earn, before anyone sets a price or an advertising budget.

Want to check whether your products really earn once every fee is deducted? Book a free consultation and profitability audit.

Sources

• Amazon, selling pricing (basis for the referral fee, including on VAT and shipping): sell.amazon.de/en/pricing (accessed 2026-07-23)
• FBA calculator and fee table: Seller Central (after login), current rates per category and country
• Break-even ACoS (industry definition): Ad Badger, adbadger.com (accessed 2026-07-23)
• VAT rates vary by EU country and product category (Germany's standard rate 19%, as of 2026): European Commission, VAT rates applied in the member states.