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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.
Type the sides in any order — the tool sorts them the way Amazon does before classifying.
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.
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.
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.
Everything computes locally in your browser. No upload, no account, no rate card needed — tiers are published rules, not quotes.
Nine tiers, from Small Standard at the bottom to Overmax at the top. A product is placed in the first tier whose every limit it fits: all three sorted sides, the unit weight, and the girth where the tier has one. The limits in force today are in the table on this page, verified 2026-09-28 against Amazon seller help pages.
Sort the three sides longest, median, shortest and compare them with the tier limits, then apply the weight limit, then the girth limit for the bulky tiers. Entering the sides in packaging-sheet order is the most common error: a 14 x 4 x 12 in box is judged as 14 / 12 / 4, and the wrong order can drop you into a cheaper tier that Amazon will not honour.
The unit as it is sold and shipped, which means the product in its own retail packaging, not the master carton it travels to the warehouse in. The master carton answers to a separate set of inbound carton rules, and confusing the two is a common source of wrong tier calls.
Two independent rule sets that get confused constantly. The size tier governs the per-unit fulfilment fee and is measured on the retail unit. The inbound carton limits govern the master carton you ship into the fulfilment centre, with a maximum length of 36 in and, unless the goods need two people or lifting equipment, 50 lb. Satisfying one says nothing about the other.
Usually one sorted side crossed a tier limit, or the weight did. Girth is the less obvious cause: on the bulky tiers, a length plus girth between 105 and 130 in forces Extra-Large even on a light item, and above 130 in the item is Overmax whatever it weighs. Shaving half an inch off the longest side is often enough to come back down.
Above the tier table there is no fee schedule to compute at all. Overmax listings need Amazon's approval before they can be sold, so an Overmax result is a product-design problem rather than a shipping one. The fix is a different pack or a different product, not a cheaper carton.
No. The tier selects which fee schedule applies, and inside that schedule the fee is driven by billable weight, which is the greater of the actual weight and the dimensional weight. Two units in the same tier can still carry different fees, and dropping a tier is usually worth far more per unit than trimming billable weight inside one.