Overview

Amazon will raise its Fulfillment by Amazon (FBA) fees beginning in 2026, ending the fee stability that characterized 2025. The adjustments increase per‑unit fulfillment costs for every standard‑size price tier and replace the parent‑ASIN low‑inventory penalty with a seller‑FNSKU‑level calculation. Sellers must reassess margins, inventory policies, and replenishment cycles now to avoid unexpected cost spikes.

Key Points

• Per‑unit fee rise — Standard‑size fulfillment fees climb between $0.05 and $0.31 per unit, depending on the product’s retail price.
• FNSKU‑level low‑inventory charge — Amazon will assess low‑inventory fees for each individual seller‑FNSKU instead of aggregating at the parent ASIN level.
• Dual‑window demand metric — The 28‑day supply trigger will be calculated using both 30‑day recent sales velocity and 90‑day historical sales data.
• End of 2025 fee freeze — After a year of flat rates, the new schedule reintroduces incremental cost increases across the board.
• Margin pressure on sub‑$10 items — A $0.05 increase on a $8 product represents a 0.6% rise in cost, potentially eroding already thin margins.

How the New Low‑Inventory System Works

1. Supply‑threshold calculation — Amazon projects the number of days of inventory remaining by dividing current on‑hand units by the average daily sales rate derived from the past 30 days. Example: A seller with 150 units and a 30‑day average of 5 units sold per day projects a 30‑day supply.
2. Historical demand overlay — The platform then blends the 30‑day rate with the average daily sales from the preceding 90 days, weighting the longer window to capture seasonal trends. Example: If the 90‑day average is 7 units per day, the combined projection may drop the estimated supply to 21 days, triggering a low‑inventory fee earlier.
3. FNSKU‑specific trigger — When the blended projection falls below 28 days for a particular seller‑FNSKU, Amazon applies the low‑inventory penalty to that SKU alone. : A ten‑color shirt listing keeps eight colors stocked but lets two colors dip to 20‑day supply; only those two colors incur the fee.