← Amazon FBA vs FBM calculator
Amazon sellers search for the low-inventory-level fee because running FBA stock close to demand is no longer free. When both the 30-day and the 90-day historical days of supply sit below 28, FBA shipments can pick up a per-unit surcharge. If either window is 28 days or more, this model adds nothing.
Days of supply is average on-hand inventory divided by average daily units shipped. The surcharge band then depends on how thin the thinner window is, plus size tier and weight. Merchant-fulfilled orders do not pay it. Grocery and new-FNSKU exemptions are switches you can turn on — they are not a claim that your account qualifies.
Restocking is not free either. Sending enough units to cover 28 days at the faster of those two sales windows adds inbound now and monthly storage on the extra cube. On the default small, fast SKU the surcharge is $26.70 / month and extra storage is $0.87, so restocking 18 units avoids $25.83 / month after storage. On a bulky SKU in peak season, paying the fee and staying thin can leave more cash.
| Policy | Days of supply | Monthly LIL | Extra storage | Monthly gap |
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Rates change by size, season, category, and account. This page does not publish Amazon’s live schedule. Paste the low-inventory-level fee from your current fee preview. Complementary to aged-inventory removal (units that already sit) and to Q4 peak storage (when the cube sits). The same listing lives on the Amazon FBA calculator.
The calculator is arithmetic, not advice. It does not recommend a restock quantity, and it does not claim a listing is profitable after you send more inventory.
This model adds a per-unit surcharge only when both the 30-day and the 90-day historical days of supply sit below 28. Days of supply is on-hand units divided by average daily units shipped in that window. If either window is 28 days or more, the page adds nothing. Merchant-fulfilled, grocery, and new-FNSKU listings can be marked exempt — that is a switch you turn on, not a claim your account qualifies.
On the calculator defaults (10 units on hand, 30 sold in 30 days and 90 in 90 days, small standard, 8×6×2 in, $0.87 storage, $1.20 inbound, 30 shipments a month) both windows are 10 days. The illustrative 0–13 day band is $0.89 / unit, or $26.70 / month. Restocking 18 units to 28 days adds $0.87 / month of storage and $21.60 inbound now, so restocking avoids $25.83 / month after extra storage. Peak storage on a bulky cube can flip that: extra storage can exceed the surcharge, so staying thin leaves more monthly cash.
No. Size-tier bands are illustrative defaults you overwrite from your current Amazon fee preview. The page does not recommend a restock quantity and does not claim a listing is profitable after you send more inventory.