Amazon FBA Fee & Unit Margin Calculator

Amazon FBA unit economics, in order

Sellers lose money when they subtract COGS from price and ignore Amazon. Fees stack in a fixed order: a category referral (with a $0.30 floor) plus an FBA pick-pack-ship fee that jumps with size tier, plus inbound freight you already paid to get the unit into a fulfillment center. Ads, storage, and returns sit on top of that stack and are not in this per-unit snapshot - if the unit is already unprofitable here, paid traffic will not save it.

Referral = max($0.30, price × rate)
Amazon fees = referral + FBA fee
Unit cost = COGS + inbound + Amazon fees
Profit = price − unit cost
Margin = profit / price
ROI = profit / (COGS + inbound)

Default $29.99 at 15% referral: max($0.30, $4.4985) = $4.50. Small Standard FBA $3.22. Amazon fees = $7.72. Landed cost $6.50 + $1.00 = $7.50. Unit cost = $15.22. Profit = $14.77 (49.3% margin). ROI on $7.50 landed ≈ 197%. If profit goes negative, the net margin card turns red (#EF4444) and the alert reads “Unit Sold at a Loss.” A selling price of $0 disables the math and the copy button so you cannot export a nonsense quote.

Referral fees, the $0.30 floor, and category rates

Most US categories charge around 15% of the total sales price (item plus shipping the buyer paid). Amazon still takes at least $0.30 even when 15% of a cheap SKU is less than that. A $1.00 accessory at 15% is $0.15 on paper and $0.30 in settlement. That floor wrecks low-price, low-margin experiments. If you sell in a category with a different posted rate - clothing often differs from electronics - change the referral field. This page does not look up your product type; it applies the rate you enter, then enforces the $0.30 minimum.

Referral is calculated on selling price, not on profit. Raising price raises the fee in dollars even as margin percent improves. Lowering price to win the Buy Box can cross the floor and erase the unit. Run both directions on this calculator before you change a live listing.

Size tiers and why the FBA field is editable

Amazon’s 2026 US FBA tables change with peak season, dimensional weight, and whether the unit is apparel. This tool’s $3.22 / $4.75 / $9.73 figures are planning bases for Small Standard, Large Standard, and Oversize - not a quote for your ASIN. Select a tier to pre-fill the fulfillment field, then overwrite it with the fee from Amazon’s revenue calculator or the fee preview on the listing. The size-tier control is a real listbox: Arrow Up/Down moves the active option, Enter and Space select, and aria-expanded plus aria-activedescendant stay in sync for assistive tech.

Packaging decides the tier more often than the product photo. A small item in a bulky mailer can jump from Small Standard to Large Standard and add more than a dollar of FBA per unit. Measure the packed unit, not the item. If you are on the edge of a tier, shrinking the box is often worth more than negotiating another $0.10 of COGS.

Margin vs ROI, and what this calculator leaves out

Net margin is profit divided by selling price - how much of the customer’s dollar you keep after Amazon and landed cost. ROI is profit divided by cash you tied up in COGS plus inbound. A cheap product can show a huge ROI and a thin margin; a premium product can show a modest ROI and a fat margin. Both numbers are on the results row because sellers argue past each other when they only quote one. A 49% margin with 197% ROI on the defaults is a healthy private-label starting point. A 8% margin with 40% ROI may still work at volume, but it will not survive a referral increase, a peak FBA surcharge, or a 10% return rate.

Not included: monthly storage, aged-inventory surcharges, returns processing, inbound placement service, AWD, and advertising. Those are real. Add a mental buffer - many operators treat 10-20% of revenue as a combined ads-and-returns haircut - and only then decide whether the unit is worth launching. If the card is already red, stop. Fix price, cost, or size tier before you spend on PPC.

Frequently Asked Questions (FAQ)