SellerSays

FBA vs FBM: run your real numbers

The honest comparison is one number against another: Amazon's official FBA fee for your exact item (computed below from the 2026 rate card, surcharge included) versus your true FBM cost per order — postage plus materials plus the labor you actually spend. For small, light, fast-turning products FBA's rate is hard to beat before you even count the Prime badge; for heavy, slow-turning, or oversized items, storage and dimensional weight often flip it to FBM. Your inputs decide.

FBA charges ≈ $6.31 per unit to fulfill this item (fee $6.1 + 3.5% surcharge).

  • FBA fulfillment fee (large-standard, 2.33 lb shipping weight, $10–50 price band) Official fact$6.1
  • Fuel & logistics surcharge (3.5%) Official factAmazon's rate tables exclude this surcharge; it is billed on top since 2026-04-17.$0.21

Assumption: Dimensional weight (2.33 lb = L×W×H ÷ 139) exceeds unit weight and is used as the shipping weight.

Assumption: Non-peak rates (peak fees apply Oct 15 – Jan 14 and run higher).

FBA is cheaper by $0.19 per unit at your numbers.

SellerSays rule — beyond the per-unit math:

  • FBA buys the Prime badge and Amazon handles returns/support; both typically lift conversion, but by how much is your data, not ours.
  • FBA adds monthly storage (and steep Oct–Dec rates), inbound freight, and aged-inventory surcharges — none are in this per-unit figure.
  • FBM keeps you off FBA capacity limits, lets you use one inventory pool across channels, and preserves your packaging/brand insert.
  • Crossing a price band ($10 / $50) or a weight band moves the fee in steps, not smoothly — check the next band before repricing.
  • Dimensional weight punishes light-but-bulky items; smaller packaging directly cuts the fee.
  • Peak season (Oct 15 – Jan 14) uses a higher table.

What the per-unit math leaves out — both directions

In FBA's favor: the Prime badge (conversion uplift that's real but yours to measure), Amazon-handled customer service and returns, and multi-warehouse delivery speed you can't replicate solo. Against it: monthly storage that triples in Q4, aged-inventory surcharges after 22 weeks, inbound freight to Amazon, capacity limits, and losing your packaging as a brand touchpoint.

Cross-border sellers have one more asymmetry: FBA requires importing inventory into the US first (customs, duty, an importer of record) — the landed cost calculator prices that step. FBM from your home country avoids the import but puts 7–14-day delivery against Prime's two days.

Common questions

Is there a rule of thumb?
Under a pound, under $50, steady sales: FBA usually wins on cost alone. Over 3 lb or slow-turning: run this calculator and include storage — that's where FBM comebacks happen. But it's a calculation, not a rule.

Official sources behind these numbers

  • 2026 US FBA product size tier definitions (effective 2026-01-15; adds the new 'small bulky' tier). Shipping weight for tier assignment = greater of unit weight and dimensional weight, except small standard and extra-large >150 lb which use unit weight only. Amazon · verified 2026-07-22 · effective 2026-01-15
  • 2026 non-peak US FBA fulfillment fees, small standard size, non-apparel, per unit, by shipping-weight band and item price band (fees exclude the 3.5% fuel and logistics surcharge). Fee weight for small standard uses unit weight only. Amazon · verified 2026-07-22 · effective 2026-01-15
  • 2026 non-peak US FBA fulfillment fees, large standard size, non-apparel, per unit, by shipping-weight band and price band (excludes 3.5% surcharge). Above 3 lb: base fee + $0.08 per 4-oz interval above the first 3 lb, up to 20 lb. Amazon · verified 2026-07-22 · effective 2026-01-15
  • Amazon applies a 3.5% fuel and logistics-related surcharge on top of FBA fulfillment fees in the US and Canada (and on FBA remote fulfillment fees from the US to Canada, Mexico and Brazil) from 2026-04-17; extended to US Buy with Prime and US/Canada Multi-Channel Fulfillment from 2026-05-02. All published fulfillment-fee rate tables explicitly EXCLUDE this surcharge, so a calculator must add 3.5% to the base fulfillment fee. Amazon · verified 2026-07-22 · effective 2026-04-17
  • Base monthly inventory storage fees per cubic foot of average daily volume: Jan-Sep (off-peak) standard-size $0.78, bulky/extra-large ('oversize') $0.56; Oct-Dec (peak) standard-size $2.40, bulky/extra-large $1.40. Dangerous goods: Jan-Sep $0.99 standard / $0.78 oversize; Oct-Dec $3.63 standard / $2.43 oversize. Amazon · verified 2026-07-22

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