How do Amazon FBA fulfillment fee tiers work?
FBA fulfillment fees are charged per unit shipped and depend on size tier and shipping weight. Tiers run from small standard (under 16 oz) through large standard, large bulky, and extra-large. Rates step up sharply at each tier boundary, so a product just over the cutoff can cost 40% more to ship.
Jul 26, 2026 · 3 min read
How the tiers work
Amazon slots every ASIN into a size tier based on the longest side, median side, shortest side, unit weight, and dimensional weight. The fee then keys off the shipping weight within that tier.
Where the tier lines matter
The biggest jumps sellers actually feel:
- Small standard to large standard around 16 oz.
- Large standard to large bulky at 18 inches longest side or over 20 lb.
- Large bulky to extra-large at 108 inches longest plus median plus shortest.
How to protect margin
Measure and weigh your product in FBA-ready packaging, not the retail box alone. A polybag change or a 0.2 oz packaging trim can drop a SKU into the lower tier and save 15% to 40% per unit for the life of the product.
Frequently asked questions
Do fulfillment fees change every year?
Yes. Amazon typically updates FBA fees each January and mid-year. Model your next 12 months at the latest published rate, not the rate you launched at.
Are dangerous goods charged more?
Yes. Hazmat items pay a fulfillment fee premium and are limited to the dangerous goods program.
Does apparel pay a different rate?
Yes. Apparel has a small surcharge on top of the standard fee in most marketplaces.
See this in Nova
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What is the aged inventory surcharge on Amazon FBA?
The aged inventory surcharge is a monthly fee Amazon adds to units that have sat in FBA warehouses for a long time. It kicks in around 181 days and grows the longer the unit sits. It is separate from long-term storage fees and stacks with monthly storage.
How do I calculate profit per unit on Amazon?
Profit per unit on Amazon equals sale price minus referral fee, FBA fulfilment fee, per-unit COGS, allocated ad spend, and a refund reserve. A quick formula: Profit/unit = Price - (Referral% x Price) - FBA fee - COGS - (Ad spend / units sold) - (Refund rate x Price).