How to Calculate Amazon FBA Profit

Almost any seller can tell you their revenue and their fees. Far fewer can tell you what one unit actually leaves behind. That is the gap this guide closes: how to calculate Amazon FBA profit per unit, with the numbers pulled from your own account instead of an average from a blog post.

The formula, per unit and per month

Net profit per unit = selling price, minus the referral fee, minus the FBA fulfillment fee, minus your landed unit cost, minus the per-unit share of monthly storage, minus the per-unit cost of returns, minus advertising spend divided by units sold.

Two of those are fixed at the moment of sale. Four of them land afterwards, and that is why a SKU can look healthy in your head and lose money in your bank account.

Per month, the same thing stated differently: net profit = payouts received, minus landed cost of units sold, minus advertising invoiced, minus storage and surcharges, minus the cost of units that came back. Both views should agree. If they do not, the gap is usually storage or returns.

Where each number comes from

Do not take fee figures from an article, including this one. Take them from the three places Amazon updates:

• The Revenue Calculator. It prices a specific ASIN with your own dimensions and weight, and Amazon's forum notice on previewing current and future costs describes an estimated fee per unit dropdown that lets you compare current rates against the next year's.
• The Fee Preview report, and the estimated fee per unit sold column in Manage Inventory. This is the per-SKU view, and it reflects your actual measured dimensions, which is the number that bites when Amazon re-measures a box.
• The payments and transaction view. This is the only place that shows what was really charged, including surcharges. Estimates are for planning; the transaction view is for truth.

For the full schedule by category and size tier, go to Amazon's own 2026 referral and FBA fee update and the matching Seller Central announcement, then look up your own category rather than trusting a rounded number. Our breakdown of the FBA fee types that show up on a single unit explains what each line is for.

Which of your SKUs pay you last?

See my numbers

A worked example, end to end

Use your own figures in each slot. The point is the order of operations, not the inputs.

Say a unit sells for $29.99 and your Fee Preview shows a referral fee of $4.50 and a fulfillment fee of $5.20 for that size tier. Your landed cost per unit, including freight, duty and prep, is $7.40.

• Selling price: $29.99
• Referral fee: minus $4.50
• Fulfillment fee: minus $5.20
• Landed unit cost: minus $7.40
• Gross margin after the obvious costs: $12.89

Now the four that arrive later.

• Storage. Divide the month's storage invoice for that SKU by the units you sold that month, not by the units you hold. Say $0.46 per unit sold.
• Returns. A returned unit costs you the return processing, the inbound back, and the loss if it comes back unsellable. Say your return rate is 6% and an average return costs you $11. That is $0.66 per unit sold.
• Advertising. Take the SKU's spend and divide by units sold, including organic ones. Say $2.10.
• Peak and surcharges. Holiday peak fulfillment fees run from October 15, 2026 to January 14, 2027, an average of $0.32 more per unit than non-peak rates, with a 3.5% fuel and logistics surcharge applied on top.

Net profit per unit in peak: $12.89 minus $0.46 minus $0.66 minus $2.10 minus $0.32, then minus the 3.5% surcharge on the fulfillment side. On these inputs the unit lands near $9.19, which is roughly 31% of the selling price. The same unit looked like 43% before the four later costs were counted. That 12-point difference is the whole reason to do this per SKU.

The numbers that move, and the dates they move on

An evergreen calculation still has dated inputs. These are the current ones:

• Since January 15, 2026, FBA fees rose by an average of $0.08 per unit sold, which Amazon frames as less than 0.5% of an average item's selling price. Amazon also said no new FBA fee types would be introduced in 2026, and that sellers get at least 90 days of notice before a fee increase.
• From October 15, 2026 to January 14, 2027, holiday peak fulfillment fees apply, averaging $0.32 more per unit, with a 3.5% fuel and logistics surcharge.
• If you replenish FBA automatically from AWD, the off-peak monthly storage rate continues through October 31, 2026.

When one of these changes, you change one line of your model. That is the test of a profit calculation built properly: it survives a fee update.

The three costs that decide the answer

Referral and fulfillment fees are the ones everybody models, and they are rarely where the money goes. Storage is seasonal and compounds with slow stock, which is why what Q4 storage actually costs belongs in the same spreadsheet. Running too lean has its own price through the low inventory level fee. And returns are the line most sellers book as a sales reduction rather than a cost per unit, which hides them completely.

For context on where your result should land, compare it against the average FBA profit margin and how it is measured. Context, not a target: your category and your freight decide more than any benchmark.

What to do with the number

Calculate it per SKU, monthly, on the same day each month. Then sort ascending. The bottom of that list is the decision: the units that pay for storage, advertising and returns without paying you. You do not need a better average. You need to know which SKUs are negative, and since when.

#FBA#tarifas#margen#finanzas

👋Hey! I'm Amara

Press at SellerKey.co

☕ Espresso. Never a latte macchiato.

I cover Amazon fee and policy changes: what changed, when it applies and where Amazon published it.

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