Free tool · runs in your browser

FBA Size Tier Calculator

Enter dimensions and weight; get the Amazon FBA size tier, dimensional weight, billable weight and how far you are from the nearest tier limit. Free, no signup.

The 2026 tier table this tool judges against

Nine tiers, verified against Amazon US seller help pages on 2026-09-28. Your product is placed in the first tier whose every limit it fits: all three sorted sides, the weight, and (for bulky tiers) the girth.

Tier	Longest (in)	Median (in)	Shortest (in)	Weight (lb)	Girth (in)
Small standard	15	12	0.75	1	—
Large standard	18	14	8	20	—
Small Bulky (new 2026-01-15)	37	28	20	50	130
Large Bulky	59	33	33	50	130
Extra-Large 0–50 lb	96	999	999	50	130
Extra-Large 50–70 lb	96	999	999	70	130
Extra-Large 70–150 lb	96	999	999	150	130
Overmax (longest side >96 in, or length+girth >130 in)	999	999	999	150	999
Extra-Large 150+ lb (unit weight only)	999	999	999	1000000000	999

Girth = longest side + 2 × (median + shortest). It only binds on the bulky tiers. "New 2026-01-15" marks the Small Bulky tier, introduced with the January 2026 fee changes.

Rules this tool applies, and where they bite

Sides are sorted first. A 14 × 4 × 12 in box is judged as 14 / 12 / 4. Sellers who enter the sides in packaging-sheet order get the wrong tier, and nothing on the fee preview explains why.

Dim weight uses a 2-inch floor on width and height for bulky tiers. For Small Bulky and everything above it, Amazon assumes the two shorter sides are at least 2 in. A genuinely flat 24 × 1 × 8 in item is billed as if it were 24 × 2 × 8. Standard tiers do not get this floor.

Girth only matters at the top. Length + girth over 130 in is Overmax regardless of weight; between 105 and 130 it forces Extra-Large even when the item is light.

Above the table there is no fee to compute. Overmax items need a special approval to sell at all, which is a product-design problem, not a logistics one.

Headroom is how far you are from the nearest limit of your own tier. Under 0.5 in or 0.5 lb it is flagged as a tier edge — the region where repacking into a slightly smaller carton, or shaving a fraction of an ounce, changes the fee schedule for every unit you ship.

From tier to money

The tier decides which fee schedule a unit lands on; the billable weight (the greater of actual and dimensional weight) feeds the fulfillment fee inside it. Two units in the same tier can carry different fees only through billable weight, and one inch can move you across tiers worth several dollars per unit. Multiply a tier mistake by your monthly volume and it usually dwarfs anything you could save negotiating freight.

Price a whole shipment in the workbench Dim weight calculator

Everything computes locally in your browser. No upload, no account, no rate card needed — tiers are published rules, not quotes.