How the estimate is built
An FBA sale has two Amazon fees that hit every unit and a few that depend on how you run your inventory:
- Referral fee: a percentage of the sale price by category, usually 15%, with a $0.30 minimum.
- Fulfillment fee: a flat fee per unit based on size tier and shipping weight. This is what you pay Amazon to pick, pack, and ship the order. It's the same whether the buyer paid $12 or $40.
- Monthly storage: charged per cubic foot your inventory takes up, and roughly three times higher from October through December.
- Inbound costs: what you pay to get units to Amazon, plus the inbound placement fee Amazon charges when you send everything to one location instead of splitting shipments.
The calculator adds those up, subtracts your landed item cost, and shows profit, margin, and return on what you paid for the item. For the full breakdown of each fee and the less obvious ones (low-inventory fees, returns processing, aged inventory surcharges), read the complete guide to Amazon FBA fees.
2026 fulfillment fee bands
| Size tier | Shipping weight | Fee per unit |
|---|---|---|
| Small standard | Up to 4 oz | about $3.20 |
| Small standard | 4 to 8 oz | about $3.38 |
| Small standard | 8 to 12 oz | about $3.58 |
| Small standard | 12 to 16 oz | about $3.70 |
| Large standard | Up to 4 oz | $3.73 |
| Large standard | 12 to 16 oz | $4.60 |
| Large standard | 1.25 to 1.5 lb | $5.42 |
| Large standard | 1.75 to 2 lb | $5.82 |
| Large standard | 2.75 to 3 lb | $6.67 |
| Large standard | 3 to 20 lb | $6.97 + $0.08 per 4 oz over 3 lb |
| Bulky | Base | about $9.73 + $0.42/lb over 1 lb |
Items priced under $10 get the low-price rate, which is about $0.86 less per unit. Apparel has its own slightly higher table. Bulky rates were restructured in 2026 and vary more by dimensions, so treat that row as a rough guide.
Monthly storage rates
| Item size | January to September | October to December |
|---|---|---|
| Standard size | $0.78 per cu ft | $2.40 per cu ft |
| Oversize / bulky | $0.56 per cu ft | $1.40 per cu ft |
Inventory that sits a long time also picks up aged inventory and storage utilization surcharges on top of these, which is why slow movers get expensive fast. A tiny item like a 0.05 cubic foot gadget costs about 4 cents a month to store in spring and 12 cents in December, but a 1 cubic foot item costs $2.40 a month in Q4.
Worked example
About a 34% margin before storage and inbound. Change the weight to 3.5 lb and fulfillment rises to $7.38, cutting profit to $6.16 even though nothing else about the listing changed.
That last line is the lesson most new FBA sellers learn after their first shipment: weight and packaging are pricing decisions. Shaving a box down so an item drops one weight band, or from large standard into small standard, can be worth more than negotiating a few cents off the unit price with your supplier.
When FBA math gets tight
Because the fulfillment fee is flat, it eats a much bigger share of cheap items. A $9.99 item in small standard still pays roughly $2.42 in fulfillment after the low-price discount and surcharge, plus $1.50 in referral. That's about 39% of the price gone before you've paid for the product. That's why a lot of sellers bundle low-priced items into multi-packs. I go through that with real numbers in how to price multi-packs and bundles.
Questions people ask
What counts as small standard size?
Items up to 16 oz that fit within 15 x 12 x 0.75 inches, like a phone case, a paperback, or a pair of tube squeezers. Anything up to 20 lb and 18 x 14 x 8 inches is large standard. Bigger or heavier items are bulky.
What weight should I enter?
Amazon bills on shipping weight, which is the item plus its packaging. For large standard items it also compares actual weight to dimensional weight (length x width x height divided by 139) and uses the higher one. If your item is light but bulky, enter the dimensional weight.
What is the 3.5% surcharge?
Starting April 17, 2026, Amazon added a 3.5% fuel and logistics surcharge to FBA fulfillment fees in the US and Canada. Amazon calls it temporary but hasn't given an end date. The box is checked by default so your estimate isn't low.
Why is my fulfillment fee lower on items under $10?
Amazon gives items priced under $10 a lower fulfillment fee. In 2026 the discount is about $0.86 per unit compared with the regular rate. The calculator applies it automatically when your price is under $10.
Does this include the Professional plan fee?
No. The $39.99 monthly Professional plan fee is a fixed cost across all your sales, not a per-unit fee. Divide it by your monthly units if you want to include it.
Rates last checked October 2026. Read how we check our numbers.