Amazon FBA size tier calculator
Your package's size tier decides most of its FBA fee. Enter the three sides and the weight: the calculator gives Amazon's 2026 US size tier, the dimensional and shipping weight it charges on, length plus girth, the cubic feet storage is billed on, the fee per unit, and which measurement keeps the item out of the next, cheaper tier.
Charged on dimensional weight: the box's volume ÷ 139 is more than the item weighs. A smaller box lowers it. The fee is today's non-peak rate with the 3.5% surcharge (both seasons).
To be small standard: shortest side 3 in, needs 0.75 in or less; weight 1.5 lb, needs 1 lb or less.
Amazon's 2026 US size tiers
| Tier | Longest | Middle | Shortest | Length + girth | Weight |
|---|---|---|---|---|---|
| Small standard | 15 in | 12 in | 0.75 in | — | 1 lb unit weight |
| Large standard | 18 in | 14 in | 8 in | — | 20 lb shipping weight |
| Small bulky | 37 in | 28 in | 20 in | 130 in | 50 lb shipping weight |
| Large bulky | 59 in | 33 in | 33 in | 130 in | 50 lb shipping weight |
| Extra-large | Anything past large bulky | ||||
An item belongs to the smallest tier whose every limit it meets. Shipping weight is the unit weight for small standard; for the other tiers the greater of the unit weight and the dimensional weight, and bulky and extra-large items count at least 2 inches of width and height. Girth is twice the middle side plus twice the shortest. From Amazon's 2026 US product size tiers in Seller Central, in use since January 15, 2026.
How it's worked out
- Dimensional weight = length × width × height in inches ÷ 139. In the example, 12 × 9 × 3 = 324 cubic inches, so 2.33 lb.
- Shipping weight = the greater of that and the unit weight: 2.33 lb against 1.5 lb, so Amazon charges the example by its box, not its weight.
- Cubic feet = cubic inches ÷ 1,728: 0.188 for the example. Monthly storage fees and the storage limits count it (the storage fee calculator prices it).
- The example is large standard. To be small standard it would need a shortest side of 0.75 in or less and a weight of 1 lb or less.
Size tier questions
Why is my size tier different in Seller Central?
Amazon measures and weighs the units it receives, and its numbers win. If they are bigger than your packaging, the item can land in a bigger tier and every unit pays more. MyProfit's fee overcharge check compares Amazon's measurements with yours and lists the products whose fee went up.
Is a smaller tier worth repacking for?
It can be: the fee changes with the tier on every unit you sell, so a slightly smaller box or a thinner pack adds up fast. Check the fee at both sizes with the FBA fee calculator before you change the packaging.
Does the size tier change the storage fee?
Yes: standard-size and oversize items have different monthly rates per cubic foot, and the storage fee is charged on the cubic feet above.
See every product's real fees, tier and profit from your own Amazon data
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