Size tier and dimensional weight calculator
Enter the packaged dimensions and weight. You'll get the 2026 size tier, the dimensional weight and the weight Amazon uses for your fulfillment fee.
| Tier | Longest side | Median side | Shortest side | Length + girth | Max weight |
|---|---|---|---|---|---|
| Small standard | 15 in | 12 in | 0.75 in | — | 16 oz |
| Large standard | 18 in | 14 in | 8 in | — | 20 lb |
| Small bulky | 37 in | 28 in | 20 in | 130 in | 50 lb |
| Large bulky | 59 in | 33 in | 33 in | 130 in | 50 lb |
| Extra-large | Anything larger or heavier than large bulky. Billed in four weight bands: 0–50, 50–70, 70–150 and 150+ lb. | ||||
How Amazon decides the size tier
Amazon sorts the three sides from longest to shortest, so it doesn't matter which you call length. The unit goes into the smallest tier whose every limit it fits: longest side, median side, shortest side, length plus girth for bulky tiers, and weight.
Length plus girth is the longest side plus twice the sum of the other two. A 37 × 28 × 20 inch box fits small bulky's side limits but measures 133 inches, over the 130-inch cap, so it is extra-large.
Dimensional weight
Dimensional weight is length × width × height ÷ 139, in inches and pounds. Large standard, bulky and extra-large units under 150 lb are billed on whichever is greater, unit weight or dimensional weight. Small standard units, and extra-large units over 150 lb, are billed on unit weight only.
For small bulky, large bulky and extra-large items Amazon treats the width and height as at least 2 inches when it computes dimensional weight, so long, thin items don't escape it.
A common mistake: a 12 oz product in a 9 × 6 × 2 inch box has a dimensional weight of 0.78 lb. It is billed in the 12–16 oz row ($4.60 in the $10–$50 band), not the 8–12 oz row ($4.20). At least one widely shared 2026 fee table makes exactly this error in its worked example. More in our dimensional weight guide.
Source: Amazon Seller Central, Product size tiers. Last checked October 18, 2026.