← Amazon FBA vs FBM calculator
Sellers search for “Amazon FBA size tier” after a fee preview jumps overnight. The referral rate did not change. The carton crossed a gate. Large standard starts when the shortest side is over 0.75 inch or the weight is over 1 lb. Extra-large starts when the longest side clears 59 inches or the girth math fails.
On the default 8×6×2 inch, 0.75 lb home-and-kitchen example, the pack is large standard. Flattening the shortest side to 0.75 inch is what classifies the same unit as small standard — if it still fits. Illustrative fulfillment drops from $4.15 to $3.38. Storage also falls with the smaller cube. Together the smaller carton keeps $0.80 more per unit, or $64.02 per month at 80 units, before extra prep. A mailer that costs $5.00 more than the current carton erases the cliff.
| Carton | Size tier | Fulfillment | FBA leftover | vs current |
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Rates change by size, season, category, and account. This page does not publish Amazon’s live schedule. Paste the fulfillment fee from your current fee preview after you change a carton. Complementary to Q4 peak storage (when the unit sits) and to Amazon inbound prep (who labels the unit). The same listing lives on the Amazon FBA calculator.
The calculator is arithmetic, not advice. It does not claim the product fits the smaller box, and it does not recommend a pack-out.
It can, when the packed cube crosses a dimensional or weight gate. On the calculator defaults — an 8×6×2 inch carton at 0.75 lb — the pack is large standard because the shortest side is 2 inches. Flattening that side to 0.75 inch classifies the same unit as small standard if it still fits. Illustrative large-standard fulfillment is $4.15 and small-standard is $3.38. Storage also falls with the smaller cube. Together the smaller carton keeps $0.80 more per unit, or $64.02 per month at 80 units, before extra prep.
No. A weight-band drop keeps the same size tier. The same 8×6×2 carton at 8 oz instead of 12 oz stays large standard and keeps $0.40 more. The page shows both rows so a cheaper ounce band is not confused with a cheaper size tier.
No. Referral, fulfillment, and storage rates are inputs. The page fills illustrative defaults a seller can overwrite from their current Amazon fee preview. Extra prep on the smaller carton is subtracted from the savings. The page does not claim the product fits the smaller box.