Amazon FBA Fee Calculator

Behind the number

Total Amazon fees on an FBA sale are the referral fee plus the fulfilment fee plus storage plus any surcharges: fees = (price × referral rate) + fulfilment fee + monthly storage + surcharges.

The referral fee is a percentage set by category, commonly 8% to 17%, with a minimum of $0.30 on most categories. The fulfilment fee is a flat amount determined by the item's size tier and shipping weight, not by its price, which is what makes FBA economics so different at different price points.

How that looks in practice

A small standard item at $29.99 weighing 12 oz. Referral at 15% is $4.50. The FBA fulfilment fee at that size and weight is $4.25. Monthly storage on a small item runs around $0.09.

Total Amazon fees are $8.84, or 29.5% of the selling price. With $8.50 of landed cost, $12.65 remains, a 42% margin.

Now the same item priced at $14.99. Referral falls to $2.25 but the fulfilment fee stays at $4.25, because it is driven by size rather than price. Fees are $6.59, or 44% of the selling price, and after $8.50 of cost the product loses money.

That is the central FBA arithmetic: the flat fee is a fixed cost per unit, so it consumes a larger share of a cheaper product. Below roughly $15 to $20, FBA becomes difficult for anything but the smallest and lightest items.

Where this breaks down

Amazon's own revenue calculator uses the fees applicable on the day and does not include your cost of goods, your inbound shipping, your prep, or the returns you will process. Several of those are larger than the fees people focus on.

Size tier is also determined by the packaged dimensions and weight Amazon measures, not the ones you declare. A product that measures a fraction over a tier boundary is charged at the higher tier on every unit, and the correction is applied retrospectively rather than flagged in advance.

Acting on it

Measure and weigh a finished, packaged unit before committing to a product, and check where it falls against the size tier boundaries. An eighth of an inch can move a product between tiers and change the fee by more than a dollar a unit.

Then model the fees at the price you will actually sell at after any promotional discounting, not at full list. A product that works at $29.99 and loses money at $22.99 is a product with no promotional headroom, which is a constraint worth knowing before launch.

The fee types that arrived after the basics

The referral and fulfilment fees are the two everyone models. The ones that surprise people are the ones added since: inbound placement fees for sending stock to fewer locations than Amazon would prefer, low-inventory-level fees when your cover falls below a threshold, aged inventory surcharges on stock held over six months, and returns processing fees in categories with high return rates.

Individually each is small. Together they can add several percentage points to the effective fee rate, and they behave differently from the base fees because they are triggered by operational choices rather than by the sale itself.

That makes them partly controllable, which is the useful part. Inbound placement fees fall if you split shipments the way Amazon asks; low-inventory fees disappear if cover stays above the threshold; aged inventory surcharges are entirely avoidable with a disposal or removal decision made in month five rather than month seven. None of that is visible in a fee calculator that models only referral and fulfilment.