Amazon FBA vs FBM

Updated 2026-08-31 · ProfitKit

FBA means Amazon stores and ships your stock. FBM means you do. Both pay the same referral fee on a sale; they differ in everything after it. Which is cheaper depends on your product's size, weight and rate of sale — not on which is generally better.

What each costs you

FBA: a fulfilment fee per unit based on size and weight, plus monthly storage based on volume, plus inbound shipping to the warehouse, plus potential long-term storage or removal charges on stock that does not move. Amazon publishes current rates in Seller Central's fee documentation; they vary by marketplace and change periodically.

FBM: your own postage, your packaging, and your time per order. No storage fee if the stock is in your home — but no free space either, and no Prime badge.

The variables that decide it

Size and weight

FBA's fee scales in bands. A small, light item is usually cheaper through FBA than you could post it yourself, because Amazon's shipping rates are far better than retail. A large or heavy item can be brutally expensive, and self-fulfilment with a negotiated courier rate may win.

Sell-through rate

Storage is charged for as long as stock sits there. Fast-moving inventory barely notices it; slow inventory accumulates storage charges and eventually long-term surcharges. Slow products are the classic FBA mistake.

Your own time

FBM's postage cost is visible. The half-hour per day picking, packing and going to the post office is not, and it is the reason FBM stops scaling. Price your time at a real rate and add it, or you are comparing an incomplete number.

Compare on one product, properly

Take a single SKU and calculate profit per unit both ways:

• FBA: price − referral fee − fulfilment fee − (monthly storage ÷ units sold per month) − landed cost − inbound shipping per unit
• FBM: price − referral fee − your actual postage − packaging − your time − landed cost

The calculator handles the FBA side directly; for FBM, enter your real postage and packaging in place of the fulfilment fee. Run both and compare profit per unit and ROI, not just the fee totals.

It is not permanent

Many sellers run both: FBA for small, fast items where the fulfilment fee beats their own postage and the Prime badge lifts conversion, FBM for bulky or slow items where storage would eat the margin. Recheck the comparison when fee schedules change or a product's sell-through shifts — the right answer moves.

Do the calculation