The Amazon low-inventory-level fee is a per-unit surcharge added to the FBA fulfillment fee when a product’s stock runs thin relative to its sales. It applies only when both the 30-day and the 90-day historical days of supply for a seller-FNSKU are below 28 days, and in 2026 it costs $0.32 to $2.09 per shipped unit depending on size tier, shipping weight and how far below 28 days you sit (Amazon Seller Central help page, data checked 2026-10-01). Keep either window at 28 days or above and the fee is zero.
This page covers only this one fee: what trips it, what it costs, who is exempt, and the restock rhythm that keeps a SKU clear of it. For every other line on your Amazon bill, see the full Amazon seller fees breakdown.
How the Low-Inventory-Level Fee Is Triggered: The Two-Window Rule
Amazon measures stock depth with a metric called historical days of supply, and it calculates it twice: once over the last 30 days (short-term) and once over the last 90 days (long-term). The rule on the official help page is explicit: “We’ll only charge a low-inventory-level fee when both the long-term historical days of supply (last 90 days) and short-term historical days of supply (last 30 days) are below 28 days (4 weeks).”
Three consequences follow from that one sentence.
- One healthy window is enough. If the 90-day figure is 40 and the 30-day figure is 20, no fee. If the 30-day figure is 35 and the 90-day figure is 12, also no fee. Amazon’s help page walks through both cases.
- The tier uses the better number. When the fee does apply, Amazon uses the greater of the two figures to pick the rate band. A SKU at 12 (long-term) and 24 (short-term) is charged at the 21–28 day rate, not the under-14 rate.
- It is per seller-FNSKU. Since January 15, 2026, Amazon calculates the metric at the seller-FNSKU level instead of the parent-ASIN level, so one thin variation no longer drags its siblings into the fee, and one healthy variation no longer covers for a thin one.
The metric is also slow on purpose. Per the help page, “The metric will be updated weekly, and the latest available historical days of supply will determine the fee rate for units shipped that week.” You are always being charged on a number that describes the recent past, not today’s shelf.
Low-Inventory-Level Fee Rates for 2026
These are the US rates Amazon lists as effective January 15, 2026 and on, read from the Seller Central help page on 2026-10-01. The fee is charged per unit at the time the customer’s order ships.
| 2026 size tier | Shipping weight | Under 14 days of supply | 14 to under 21 days | 21 to under 28 days |
|---|---|---|---|---|
| Small standard | Up to 16 oz | $0.89 | $0.63 | $0.32 |
| Large standard | Up to 3 lb | $0.97 | $0.70 | $0.36 |
| Large standard | 3+ lb to 20 lb | $1.11 | $0.87 | $0.47 |
| Small Bulky | Up to 50 lb | $1.85 | $1.02 | $0.51 |
| Large Bulky | Up to 50 lb | $2.09 | $1.15 | $0.57 |
Source: Low-inventory-level fee, Amazon Seller Central, data checked 2026-10-01.
Two details from the same page matter for reading the table. Small standard uses unit weight; large standard uses the greater of unit weight or dimensional weight, so the size tier and weight rules decide which row you are in before days of supply decides the column. And Small Bulky and Large Bulky only entered the fee on January 15, 2026. Before that date the fee applied to standard-size products only, which is why older articles still describe it as a standard-size charge.
The cost scales with volume, not with how much stock you are missing. A large-standard SKU under 3 lb that ships 300 units in a month while sitting in the 21–28 day band pays 300 × $0.36 = $108. Let the same SKU slide under 14 days and the month costs 300 × $0.97 = $291, on top of the lost sales a near-stockout usually brings.
How Historical Days of Supply Is Calculated
The formula is a ratio of two daily averages over each window:
Historical days of supply = average daily inventory units ÷ average daily shipped units
Amazon’s worked example on the help page: 243.6 average daily inventory units over 5.8 average daily shipped units gives a long-term figure of 42.0; 220.5 over 12.6 gives a short-term figure of 17.5. FBA Inventory displays the greater of the two, 42.0, and that product pays no fee.
What counts on each side of the ratio is where most sellers misread their own position:
| Component | Counts | Does not count |
|---|---|---|
| Average daily inventory units | Units available for sale, units transferring between fulfillment centers, units in fulfillment center processing, all in the US fulfillment network | Unsellable units (pending removal, disposal or liquidation) and units still being inbounded |
| Average daily shipped units | All units shipped from the US fulfillment network: FBA, Multi-Channel Fulfillment, Remote Fulfillment with FBA and other programs | Units you fulfill yourself outside Amazon’s network |
The inbound exclusion is the one that bites. A shipment sitting in a carrier’s truck or waiting at the receiving dock does nothing for the metric until Amazon receives it. The MCF inclusion is the other trap: orders from your own website fulfilled through Multi-Channel Fulfillment raise the shipped-units denominator, which lowers days of supply even though your Amazon sales did not change.
Because it is an average, the metric does not require you to hold 28 days of stock every single day. A SKU on a sawtooth pattern (restock, sell down, restock) can dip below 28 days on hand for part of the cycle and still average above 28 over 30 days. That is the lever the restock rhythm below uses.
Who Is Exempt From the Low-Inventory-Level Fee
The help page lists five cases where the fee does not apply (checked 2026-10-01):
- New Professional sellers, for the first 365 days after the first inventory-received date.
- New-to-FBA parent products, for the first 180 days after the first inventory-received date, if you are enrolled in FBA New Selection.
- SKUs where 70% or more of the inventory was auto-replenished through Amazon Warehousing and Distribution over the prior 90 days.
- Products that have sold less than 20 units in the past 7 days.
- The Grocery category.
The New Selection exemption has two published versions. The help page above says 180 days for new-to-FBA parent products. Amazon’s Seller Forums announcement of the New Selection Program (2026) says, for new FBA ASINs launching from July 30, 2026: “No low-inventory-level fee and storage utilization surcharge on your first 200 units for the first 120 days” (News_Amazon, checked 2026-10-01). Amazon has not published how the two terms interact for a product that qualifies under both. The same announcement says that after October 31, 2026 you must confirm enrollment in the 2026 program to keep receiving its benefits. We plan launches on the shorter, unit-capped 120-day window and treat anything beyond it as a bonus.
The AWD exemption is the only one you can opt into on an existing SKU. If a product’s supply chain already runs through Amazon Warehousing and Distribution, turning on auto-replenishment for it moves the fee problem to Amazon.
Working Through the Math: Four Scenarios
Amazon’s help page gives four worked cases. Each one isolates a single rule.
| Case | Long-term (90 days) | Short-term (30 days) | Figure used | Fee result |
|---|---|---|---|---|
| 1 | 18 | 24 | 24 | $0.36 per unit (21–28 band) |
| 2 | 40 | 20 | 40 | $0.00, long-term is at or above 28 |
| 3 | 12 | 35 | 35 | $0.00, short-term is at or above 28 |
| 4 | 12 | 15 | 15 | $1.15 per unit (14–21 band) |
Source: Amazon Seller Central low-inventory-level fee help page, checked 2026-10-01.
Case 2 is the Prime Day pattern. A deal spike pushes shipped units up and short-term days of supply down, but the 90-day window still carries months of normal demand, so the fee does not fire. Amazon’s own wording: “The trailing 90-day metric ensures that the seller does not incur the low-inventory-level fees based on sudden increases in demand.”
Case 3 is the recovery pattern. After a long thin stretch, the 90-day figure is stuck low for weeks, but a large inbound that lands and lifts the 30-day figure above 28 clears the fee straight away. The help page says the same thing directly: you can avoid the fee by sending in enough units that short-term days of supply exceeds 28, or by managing the long-term figure.
A Restock Rhythm That Stays Above the 28-Day Line
The fee is an inventory-planning problem, so the fix is a reorder rule rather than a one-off shipment. This is the rhythm we use for a replenishable SKU.
Step 1: Set a target, not a floor. Aim for 35 to 45 days of supply, not 28. The metric updates weekly and describes the past, so a SKU that is sliding reaches 28 before you see it. Amazon’s own car-accessory example keeps 45 to 55 days to avoid the fee.
Step 2: Build the reorder point from lead time plus the target. Reorder point = daily sales × (total lead time + target days of supply). Total lead time must run to received, because inbound units do not count. A SKU selling 10 units a day with a 45-day lead time (production, freight, check-in) and a 35-day target reorders when available units fall to 10 × 80 = 800.
Step 3: Check the average, not the low point. For a sawtooth cycle, average on-hand is roughly safety stock plus half the reorder quantity. At 10 units a day with a monthly order of 300 units, safety stock of 130 units gives an average of about 130 + 150 = 280 units, or 28 days. That is the break-even point, so we would carry 180 to 200 units of safety stock to leave a margin.
Step 4: Split shipments instead of batching them. Two smaller inbounds a month hold the average up with less peak inventory than one large one. Weigh that against inbound placement and storage costs in the FBA storage fees guide; holding more stock trades this fee for storage cost and can pressure your IPI score and monthly capacity limit.
Step 5: Automate the check. A weekly look at days of supply by FNSKU is the whole control. A standing inventory tracking system or dedicated restock software turns it into an alert. Apply the rhythm only to SKUs that pass a replenishability test; a one-off buy you do not plan to restock will fall under the line anyway.
Where the Fee and the Metric Show Up in Seller Central
Per the help page (checked 2026-10-01), Amazon surfaces the fee in four places. We have not viewed these screens ourselves; the descriptions below are Amazon’s.
- FBA Inventory shows historical days of supply (the greater of the two windows, with both listed for reference), a Low-inventory-level fee column, and an Estimated fee per unit sold column.
- SKU Economics report has a low-inventory-level fee column showing the amount charged per FNSKU.
- Payments, Transaction View: search an order ID, open Transaction Details, and use the FBA Pick & Pack Fee link to reach the fulfillment fee explainer, which shows whether the fee was charged on that order.
- Revenue Calculator and Profit Analytics are listed as fee-estimating tools.
Common Mistakes
- Counting inbound stock as cover. Units in transit are excluded until received. Run the reorder point on received dates.
- Forgetting MCF volume. Off-Amazon orders fulfilled through MCF count as shipped units and shrink your days of supply.
- Reading one variation as the whole listing. Since January 15, 2026 the metric is per seller-FNSKU. Check each variation.
- Assuming Bulky items are exempt. Small Bulky and Large Bulky carry the highest rates in the table since January 15, 2026.
- Over-correcting. Stocking 120 days to escape a $0.36 fee can cost more in storage and capacity than the fee itself. Aim for the 35 to 45 day band, not a warehouse full.
Frequently Asked Questions
What is the Amazon low-inventory-level fee?
It is a per-unit charge Amazon adds to the FBA fulfillment fee when both a seller-FNSKU’s 30-day and 90-day historical days of supply fall below 28 days. In 2026 it ranges from $0.32 to $2.09 per unit shipped (Amazon Seller Central, checked 2026-10-01).
How do I avoid the FBA low inventory fee?
Keep at least one of the two windows at 28 days of supply or above. In practice that means setting reorder points from received-date lead time plus a 35 to 45 day target, and sending stock before the weekly metric shows the drop.
Does the low-inventory-level fee apply to slow sellers?
No. Amazon exempts products that have sold less than 20 units in the past 7 days, as well as the Grocery category (help page, checked 2026-10-01).
Do new sellers pay the low-inventory-level fee?
Not at first. New Professional sellers are exempt for 365 days after their first inventory-received date, and eligible new products get a separate New Selection exemption, published by Amazon as 180 days on the help page and as the first 200 units for 120 days in the New Selection Program (2026) announcement.
Conclusion
The low-inventory-level fee is triggered by one number measured twice. Keep either the 30-day or the 90-day historical days of supply at 28 or above for each FNSKU and it never applies. Plan to a 35 to 45 day target, count only received stock, and check the metric weekly.