Amazon Low-Inventory-Level Fee Calculator
Check an FNSKU's historical days of supply, see whether Amazon's low-inventory-level fee applies, and how much stock clears it.
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Low-inventory-level fee
$0.36 per unit
Historical days of supply is 21.4, the greater of 21.4 (long-term) and 15.6 (short-term). Both are under 28, so Amazon adds $0.36 to the fulfillment fee on each unit shipped.
- Long-term days of supply
- 21.4
- Short-term days of supply
- 15.6
- Fee per month
- $172.80
To clear 28 days on the 30-day measure you need about 448 units in stock on average, 198 more than now. It's an average over 30 days, so a new shipment lifts it gradually.
Breakdown
- Long-term: stock ÷ units shipped (90 days)
- 300 ÷ 14 = 21.4
- Short-term: stock ÷ units shipped (30 days)
- 250 ÷ 16 = 15.6
- Historical days of supply (the greater)
- 21.4
- Fee per unit shipped
- $0.36
- Units shipped next month
- 480
- Average stock for 28 days of supply (30-day sales)
- 448 units
When the low-inventory-level fee applies
Amazon adds a low-inventory-level fee to the FBA fulfillment fee on every unit shipped when a product's stock runs low compared with its sales. Since 15 January 2026 it's measured per FNSKU, not per parent ASIN, and it covers small and large bulky items too. Rates last checked 30 Sep 2026.
- The fee applies only when both the long-term and short-term figures are under 28 days.
- The rate depends on size tier, shipping weight and which band the greater figure falls in: under 14 days, 14 to under 21, or 21 to under 28.
- Stock counts sellable units in US fulfillment centers, including units moving between them and units in processing. Units still being inbounded don't count.
- Amazon updates the figure weekly. The latest one sets the rate for units shipped that week.
| Size tier | Shipping weight | Under 14 days | 14 to 21 days | 21 to 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+ 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 |
Worked example (the calculator's starting values)
- Product
- Large standard, up to 3 lb
- Long-term days of supply
- 300 ÷ 14 = 21.4
- Short-term days of supply
- 250 ÷ 16 = 15.6
- Greater of the two
- 21.4, and both are under 28
Fee $0.36 per unit, or $172.80 on 480 units a month. To clear 28 days on the 30-day measure you'd need about 28 × 16 = 448 units in stock on average.
Who doesn't pay it
- New Professional sellers, for 365 days after their first inventory is received.
- New-to-FBA parent products enrolled in FBA New Selection, for their first 180 days.
- SKUs with 70% or more of their inventory auto-replenished through Amazon Warehousing and Distribution (AWD) over the prior 90 days.
- Products that sold fewer than 20 units in the past 7 days.
- The Grocery category.
- Extra-large items: the fee covers standard-size and bulky items only.
Keeping clear of the fee
- Hold four to eight weeks of cover. In Amazon's own example, a seller keeps 45 to 55 days of supply and never pays the fee.
- Ship smaller and more often instead of letting stock run close to zero between big shipments.
- Check FBA Inventory weekly. It shows historical days of supply, with the long-term and short-term detail, and a low-inventory-level fee column.
- Confirm what you were charged in the SKU Economics report, or look up an order in Payments Transaction View.
- Keep channels separate. If the same products sell on your Shopify or WooCommerce store, a spike there shouldn't come out of your FBA stock. Track FBA units apart from your own warehouse count.
Questions people ask
What is the Amazon low-inventory-level fee?
A per-unit fee added to the FBA fulfillment fee when a product's historical days of supply is under 28 days on both the 90-day and 30-day measures. In 2026 it runs from $0.32 to $2.09 per unit.
How do I check my historical days of supply?
Open FBA Inventory in Seller Central. It shows one figure (the greater of long-term and short-term) plus the detail behind it.
Is the fee charged per ASIN or per variation?
Per FNSKU since 15 January 2026. Before that, Amazon measured it at the parent-ASIN level.
Do units on their way to Amazon count as stock?
No. Units still being inbounded aren't counted, and neither are unsellable units such as those pending removal.
Does the 3.5% surcharge apply to this fee?
Amazon's surcharge notice covers fulfillment fees but doesn't mention this fee by name, so the calculator shows it without the surcharge. Check a settled order in Transaction View to see how it was charged.
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Want this builtinto your store?
I'm Emmanuel, a Shopify and WooCommerce developer. If this tool pointed at something you'd rather have fixed for you (a faster store, cleaner product data, a migration, a custom feature), send me a note.
Emmanuel Asika
Shopify & WooCommerce developer, Dublin
I build and fix online stores: new builds, migrations, speed, SEO and the custom bits apps can't do.
Last reviewed 30 September 2026.
Sources: Amazon: Low-inventory-level fee · Amazon: 2026 US referral and FBA fee changes summary · Amazon: 2026 US FBA fulfillment fee changes