Amazon · Fulfilled by Amazon

Profit Margin Calculator for Amazon FBA

Q: Why is storage a separate line?

Storage is billed monthly per cubic foot and jumps about 3–4× in Q4. Entering it separately keeps your non-peak and peak planning honest.

Model the full FBA cost stack — category referral fee, the size-and-weight fulfilment fee, monthly storage and inbound shipping — so the net margin you see is the one you'll actually keep.

What FBA really costs per unit

FBA bundles fulfilment into one fee — but storage and inbound freight are easy to forget.

With FBA, Amazon picks, packs, ships and handles most customer returns. You pay a referral fee (8–20% by category) plus a fulfilment fee set by the unit's size and weight tier. On top of that sit two costs sellers routinely omit:

Monthly storage — Amazon charges per cubic foot, and the Q4 rate (Oct–Dec) runs roughly 3–4× the rest of the year. Enter your allocated per-unit monthly storage; plan peak separately.
Inbound shipping — getting inventory to an Amazon fulfillment center (often via partnered carrier or freight).

Use the Estimate FBA fee panel to fill the fulfilment fee from weight and dimensions, or pick a size-tier preset. Everything else — COGS, PPC, landed/import duty, a returns allowance — stacks on top.

Worked example

Price $29.99, COGS $7.50, inbound $3.50, FBA fee $4.75, storage $0.40, landed $0, PPC $2.00, returns 3%, on Home & Kitchen (15% referral):

Line	Amount
Referral fee (15%)	$4.50
FBA fulfilment	$4.75
Inbound shipping	$3.50
Monthly storage	$0.40
COGS + PPC + landed	$9.50
Returns allowance (3%)	$0.90
Net profit / unit	$6.44 (21.5% margin)

Switch the platform switcher to Amazon FBM with the same numbers to see how dropping FBA changes the stack.

Amazon FBA — FAQ

How is the FBA fulfilment fee set?

By the unit's size and weight tier (2026 US rates, non-peak, non-apparel). Use the Estimate panel above, or a preset, or type your actual fee from Seller Central.

Why is storage a separate line?

Storage is billed monthly per cubic foot and jumps ~3–4× in Q4. Entering it separately keeps your non-peak and peak planning honest instead of burying it in "fulfilment."

Does FBA include return costs?

Amazon absorbs most customer-return logistics within the FBA fee, but you still lose the refunded item. The returns allowance (% of price) models that lost revenue.

Is the referral fee the same as FBM?

Yes — Amazon charges the category referral fee whether you use FBA or FBM. The difference is fulfilment: FBA adds the fulfilment fee and storage; FBM replaces them with your own shipping, packaging, labor and return handling.