Amazon FBA low-inventory-level fee 2026: the 28-day rule and rates
The FBA low-inventory-level fee is a per-unit charge added on top of your normal fulfillment fee when a product runs too lean at Amazon's fulfillment centers. The trigger is narrower than most sellers think: it only applies when your historical days of supply are under 28 on both the trailing 30-day window and the trailing 90-day window at the same time. If either window is 28 days or more, there is no fee. This page explains the exact trigger, the 2026 per-unit rates, what changed on January 15, 2026, who is exempt, and how to set a reorder point that keeps you clear. These figures are as of 2026 for the US — confirm the current fee card in Seller Central. To see whether this fee is already landing on your SKUs, run your settlement report through the free SettleClear tool.
What actually triggers the fee
The fee is not charged simply because your stock is low today. It is charged on units shipped while your historical days of supply is under 28 on two windows at once:
- Your trailing 30-day days of supply is under 28, and
- Your trailing 90-day days of supply is under 28.
Both conditions have to be true in the same assessment. If either window sits at 28 days or more, no fee applies. This "both windows" design is meant to catch products that are chronically thin, not products that had one quiet week. The check is run weekly, and the fee is charged per unit on top of the normal fulfillment fee — it does not replace it.
How days of supply is calculated
Days of supply is your average daily inventory divided by your average daily units shipped, measured over each window:
- Average daily inventory — the typical quantity of the product sitting in FBA over the window.
- Average daily units shipped — how many units per day left the fulfillment center over the same window.
A fast-selling product needs more units on hand to clear 28 days than a slow one does, so the same unit count can be "fine" for one SKU and "under supply" for another. Because the two windows move at different speeds, a product can be under 28 on the 30-day window after a sales spike while still above 28 on the 90-day window — and in that case there is still no fee, because both windows must be under 28. The assessment is weekly, so the number you are judged on shifts each week.
The 2026 per-unit rates
The per-unit rate depends on the product's size tier and on how far under 28 days your supply has fallen. There are three supply bands: 21–27 days (mildly short), 14–20 days (short), and 0–13 days (severely short). The deeper the shortfall, the higher the per-unit charge. As of 2026 for standard-size products in the US:
| Size tier | 21–27 days | 14–20 days | 0–13 days |
|---|---|---|---|
| Small standard (up to 16 oz) | $0.32 | $0.63 | $0.89 |
| Large standard (up to 3 lb) | $0.36 | $0.70 | $0.97 |
| Large standard (3–20 lb) | $0.47 | $0.87 | $1.11 |
Since January 15, 2026, bulky products are also in scope. At the lowest supply band (0–13 days), small bulky runs up to roughly $1.85 per unit and large bulky up to roughly $2.09 per unit. Extra-large is not included. Treat every figure above as the shape of the fee rather than a locked rate — Amazon revises the card, so confirm the current per-unit amounts for your size tier in Seller Central. In practice the highest per-unit rates land on your heaviest, thinnest-stocked SKUs, which is exactly where a per-unit surcharge does the most damage to margin.
What changed on January 15, 2026
Three changes took effect on January 15, 2026 that widen who can be hit:
- Measured per seller-FNSKU, not parent ASIN. Each variation is now judged on its own stock, so a well-supplied color or size no longer shields a thin one under the same parent listing. A single lean variation can incur the fee on its own.
- Bulky is now in scope. Small and large bulky products were added to the fee. Extra-large remains excluded.
- Grocery is exempt. Grocery products are carved out of the fee entirely.
The per-FNSKU change is the one most likely to surprise sellers with variation-heavy catalogs, because a listing that looked "in supply" at the parent level can still generate fees on individual children.
Who is exempt
Several categories are exempt from the low-inventory-level fee. As of 2026:
- New professional sellers, for their first 365 days.
- New FBA products / FBA New Selection, for the first 180 days.
- Products that shipped fewer than 20 units in the trailing 7 days.
- Grocery products.
- Inventory auto-replenished through Amazon Warehousing and Distribution (AWD) — roughly when AWD supplies 70% or more over the trailing 90 days.
Note what is not on that list: there is no seasonal exemption. Running thin over a slow season or after a Q4 draw-down does not spare you. If you deliberately let a mature SKU run lean between restocks, the low-supply exemption for very low-volume products (under 20 units in the trailing 7 days) may be the only thing keeping you out of the fee — confirm your own thresholds in Seller Central.
How to set a reorder point that clears the fee
Because the fee is about days of supply and not a fixed stock number, the fix is a reorder point measured in days, not units. Aiming for exactly 28 days leaves no margin — by the time replenishment arrives you are already under. Build the full replenishment pipeline into your target:
Reorder point (days) = 28 + supplier production + transit + customs + Amazon receiving/check-in + your reaction time.
- Amazon receiving and check-in alone typically runs 5–14 days, and longer in Q4.
- Supplier production, transit, customs, and your own reaction time stack on top of that.
Add those up and a practical target is around 35 days of supply, not 28 — the extra buffer absorbs the check-in lag and normal demand variance. Once you cross the threshold, the fee stops at the first weekly assessment where at least one window is back above 28, so getting stock received and counted before that assessment is what ends the charge. If you are watching the opposite end of the inventory clock, note that overshooting the buffer pushes you toward aged and peak storage charges instead — see Amazon Q4 FBA storage fees for the surcharge that hits stock that sits too long.
See it in your own numbers
SettleClear reads your Amazon settlement report (Flat File V2) entirely in your browser — nothing is uploaded — and surfaces the per-unit fees charged against each SKU, so you can see whether a low-inventory-level fee has been landing and on which products. Pairing that with a look at your thinnest, fastest-selling SKUs shows you where a lean-stock surcharge is quietly eating margin. To find the products where fees are outrunning contribution, see how to find your losing SKUs.
Related: every FBA fee type and how it's calculated · Q4 storage fees, the opposite-end surcharge · find your losing SKUs · fee glossary.