FBA size tier calculator
Amazon US product size tiers

Enter the packaged product and its weight. Get the size tier Amazon will assign, the weight used for the fee, which limit keeps it out of a smaller tier — and the size that would reach the next tier down.

Rules verified 22 Sep 2026Checked against the official rules: Amazon Seller Central — Product size tiers · Amazon — 2026 US FBA fulfillment fee changes. Carriers change these rules, usually each January and July — see what changed and when, and confirm against your own rate sheet or account.
Packaged product size

Measure the product as packaged and ready to ship. Order doesn’t matter — the tool sorts the sides.

Amazon’s rules

US product size tiers

Amazon sets the tier from the packaged product’s longest, median and shortest sides, its length + girth, and its shipping weight — the greater of unit weight and dimensional weight (L × W × H ÷ 139). For Small Bulky, Large Bulky and Extra-Large, dimensional weight assumes a width and height of at least 2 inches.

TierShipping weightLongestMedianShortestLength + girth
Small standard≤ 16 oz≤ 15 in≤ 12 in≤ 0.75 in—
Large standard≤ 20 lb≤ 18 in≤ 14 in≤ 8 in—
Small Bulky≤ 50 lb≤ 37 in≤ 28 in≤ 20 in≤ 130 in
Large Bulky≤ 50 lb≤ 59 in≤ 33 in≤ 33 in≤ 130 in
Extra-Largeanything larger or heavier, banded 0–50, 50+–70, 70+–150 and 150+ lb

Rules verified 22 Sep 2026 · sources: Amazon Seller Central — Product size tiers · Amazon — 2026 US FBA fulfillment fee changes

When a product misses a smaller tier, the tool works backwards: it caps each side at that tier’s limit, then shrinks all three together until the length + girth and the dimensional weight fit as well, and prints the size and shipping weight that would get you there. Because dimensional weight goes with volume, trimming one long side often does more than shaving a little off all three — and sometimes the size that clears the next tier down clears the one below it too, which is what the suggestion reports.

Fees for Small standard and Extra-Large 150+ lb use unit weight only; the other tiers use the greater of unit and dimensional weight. Extra-Large items up to 150 lb that are over 96 in long or 130 in length + girth are “Overmax” and pay an extra handling fee.

FAQ

Questions

How do I find my Amazon FBA size tier?
Measure the packaged product, sort the sides into longest, median and shortest, and work out the shipping weight — the greater of the unit weight and the dimensional weight (L × W × H ÷ 139). The tier is the smallest one whose side, length + girth and weight limits all fit.
Why is my product Large standard when it weighs under a pound?
Small standard needs the shortest side to be 0.75 inch or less, the longest 15 inches or less and the median 12 inches or less, as well as a shipping weight of 16 oz or less. A product thicker than 0.75 inch is Large standard however light it is.
Does Amazon use dimensional weight for the size tier?
Yes. Amazon’s Product size tiers page says the shipping weight used to set the tier is the greater of unit weight and dimensional weight. So a light but bulky product can land in a larger tier — for example Extra-Large when its dimensional weight is over 50 lb.
How do I get my product into a smaller FBA size tier?
Work out which limit puts it in the larger tier — a side, length + girth, or the shipping weight — and fix that one. The calculator prints the packaged size and shipping weight that would reach the next tier down, or says so when the unit weight alone is already over that tier’s limit and no packaging change can help.
Is this the FBA fee?
It’s the tier and the weight band the fee is looked up in. The fee itself also depends on the product’s price band, the season (peak from 15 October 2026) and apparel or dangerous-goods status, so check Amazon’s rate card for the figure.