Home / Blog / Fees & Profit
Amazon FBA Size Tiers and Dimensional Weight (2026)
Amazon FBA (Fulfillment by Amazon) puts every product into a size tier: small standard, large standard, small bulky, large bulky or extra-large. The tier, plus the shipping weight, sets your fulfillment fee. For large standard and bigger items, shipping weight is the greater of the unit weight and the dimensional weight, which is length × width × height (in inches) ÷ 139.
Key takeaways
- Small standard means 15 × 12 × 0.75 inches or smaller and 16 oz or lighter. It uses unit weight only.
- Large standard means 18 × 14 × 8 inches or smaller and 20 lb or lighter. Dimensional weight applies.
- Bulky tiers start the moment any side exceeds the large standard limits, and fees jump sharply.
- A quarter-inch of packaging can move a product up a tier and cost thousands of dollars a year.
- Amazon uses its own measurements, so check what it has on file after your first shipment.
Amazon FBA size tiers (US, 2026)
A product must fit every limit in a row to qualify for that tier. Sides are sorted: longest, median (middle) and shortest. Measurements are of the packaged unit as it ships.
| Size 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 above large bulky | Bands: 0–50, 50–70, 70–150, 150+ lb |
Length + girth = longest side + 2 × (median side + shortest side).
The small bulky tier sits between large standard and large bulky. It covers products such as bed pillows, small rugs and larger kitchen appliances that are just too big for large standard.
How dimensional weight works
Carriers charge for space as well as weight. A big, light box takes up as much room on a truck as a heavy one. Amazon handles this with dimensional weight.
Dimensional weight (lb) = length × width × height (inches) ÷ 139
Shipping weight = the greater of unit weight and dimensional weight
Which tiers use it:
| Tier | Weight used for the fee |
|---|---|
| Small standard | Unit weight only |
| Large standard | Greater of unit weight or dimensional weight |
| Small bulky and large bulky | Greater of unit weight or dimensional weight, with width and height treated as at least 2 inches |
| Extra-large (up to 150 lb) | Greater of unit weight or dimensional weight, minimum 2 inches |
| Extra-large (over 150 lb) | Unit weight only |
The 2-inch minimum matters for flat, wide products like whiteboards or mats. Even a 0.5 inch thick board is calculated as if it were 2 inches thick for dimensional weight.
Fees are charged in weight bands, so Amazon rounds your shipping weight up to the next band. Large standard bands go up in 4 oz steps to 3 lb, then $0.08 for each extra 4 oz up to 20 lb.
Fee impact by tier
Here are sample 2026 fulfillment fees for the $10–$50 price band (non-apparel, non-dangerous goods, before the 3.5% fuel and logistics surcharge and before holiday peak fees):
| Tier and weight | Fee |
|---|---|
| Small standard, up to 2 oz | $3.32 |
| Small standard, 14–16 oz | $3.96 |
| Large standard, up to 4 oz | $3.73 |
| Large standard, 12–16 oz | $4.60 |
| Large standard, 1.75–2 lb | $5.82 |
| Large standard, 2.75–3 lb | $6.67 |
| Large standard, 3–20 lb | $6.97 + $0.08 per 4 oz above 3 lb |
Bulky tiers start higher and add a per-pound charge on top. Items under $10 pay less (large standard is $0.82 lower) and items over $50 pay a little more (large standard is $0.26 higher). Our FBA fees 2026 guide has the full picture, including storage and surcharges.
Worked example 1: A fraction of an inch that costs $4,200 a year
Say you sell a screen protector kit for $14.99. It weighs 1.8 oz packed.
Packaging A: 7 × 4 × 0.5 inches. That fits small standard (shortest side ≤ 0.75 in, weight ≤ 16 oz). Fee: $3.32. Dimensional weight doesn't apply.
Packaging B: 7 × 4 × 0.8 inches (a thicker box insert). The shortest side is now over 0.75 inches, so it becomes large standard. Dimensional weight = 7 × 4 × 0.8 ÷ 139 = 0.16 lb, about 2.6 oz. That's in the "up to 4 oz" band. Fee: $3.73.
The difference is $0.41 per unit, or about $0.42 with the 3.5% surcharge. At 10,000 units a year, that 0.3-inch change costs around $4,200.
Worked example 2: Shrinking a bulky pillow
Say you sell a bed pillow for $34.99. It weighs 2.2 lb. Here's how three packaging options compare.
| Packaging | Tier | Dimensional weight | Shipping weight | Fulfillment fee (est.) |
|---|---|---|---|---|
| 20 × 14 × 6 in box | Small bulky (longest side over 18 in) | 12.09 lb | 12.09 lb | About $12.11 |
| 18 × 14 × 6 in, folded | Large standard | 10.88 lb | 10.88 lb | $9.53 |
| 14 × 10 × 5 in, vacuum-packed | Large standard | 5.04 lb | 5.04 lb | $7.69 |
How the numbers work:
- Folded (18 × 14 × 6): 1,512 ÷ 139 = 10.88 lb. That's 7.88 lb above 3 lb, which rounds up to 32 quarter-pound steps. $6.97 + (32 × $0.08) = $9.53.
- Vacuum-packed (14 × 10 × 5): 700 ÷ 139 = 5.04 lb. That's 2.04 lb above 3 lb, or 9 quarter-pound steps. $6.97 + (9 × $0.08) = $7.69.
- Small bulky box: based on the 2026 small bulky rate of $7.55 plus $0.38 per lb above the first pound, roughly $12.11. Confirm your exact figure in the Fee Preview report.
The pillow weighs 2.2 lb in every case. You pay for the box. Vacuum packing saves about $4.40 per unit on fulfillment. It also cuts storage: the box drops from 0.97 cubic feet to 0.41, and moves from the oversize storage group to standard-size.
Before you compress a product, check that it recovers properly when opened and that reviews won't suffer. A cheaper fee isn't worth a jump in returns.
Run your own packaging options through our free FBA Profit Calculator to see the margin effect of each one.
How to check the size tier Amazon has for your product
- Go to Reports > Fulfillment > Fee Preview in Seller Central. Download the report. It lists the longest, median and shortest side, unit weight, size tier and estimated fee for each ASIN.
- Compare Amazon's dimensions with your own measurements of the packed unit.
- Check after every new shipment of a changed design. Amazon measures at the fulfillment center and its numbers win.
If Amazon's measurements look wrong, open a case with Seller Support and ask for a re-measurement. Give your measurements and, ideally, photos of the packed unit next to a tape measure. Overcharges from a wrong tier can add up on every single unit sold.
How to lower your size tier
- Measure the packed unit, not the product. Inserts, hang tabs and blister packs all count.
- Target tier edges. Know the limits that matter for your product: 0.75 inches for small standard, 18 × 14 × 8 inches for large standard.
- Cut empty space. Dimensional weight charges for air. A smaller box often saves more than a lighter product.
- Fold, roll or compress soft goods. Bedding, cushions and apparel often fit a lower tier when folded or vacuum-packed.
- Check flat items against the 2-inch rule. Large flat products in bulky tiers are billed as at least 2 inches thick for dimensional weight.
- Rethink multi-packs. Bundling can push a product over 20 lb or 18 inches. Compare fees per unit sold, not per box.
Common mistakes
- Quoting product dimensions instead of packed dimensions. Your supplier's spec sheet may not include the retail box.
- Ignoring dimensional weight because the item is light. Light and bulky is exactly when it bites.
- Not checking Amazon's measurements. A small measuring error can push you up a band or tier.
- Changing packaging without updating the listing. New packaging should go with updated dimensions, then a check of the Fee Preview once stock arrives.
- Forgetting storage. Bigger boxes also pay more storage every month. See our storage fees and aged inventory guide.
Bottom line
Your size tier and shipping weight set your FBA fulfillment fee, and for anything larger than small standard, dimensional weight (L × W × H ÷ 139) often decides the price. Measure the packed unit, design packaging around tier limits, and check what Amazon has on file in the Fee Preview report. Small packaging changes are often the cheapest margin gain you'll find.
Frequently asked questions
What is the dimensional weight divisor for Amazon FBA in the US?
Amazon US uses 139. Multiply length by width by height in inches and divide by 139 to get dimensional weight in pounds. Amazon then charges on the greater of this figure and the unit weight for large standard and bigger items.
Does dimensional weight apply to small standard items?
No. Small standard items, up to 15 x 12 x 0.75 inches and 16 oz, are charged on unit weight only. Dimensional weight applies to large standard, small bulky, large bulky and extra-large items, except extra-large items over 150 lb.
How do I change the size tier Amazon has for my product?
Amazon measures products at the fulfillment center and uses its own dimensions. If you believe they are wrong, contact Seller Support and ask for a re-measurement. If you change the packaging, update the dimensions in your listing and expect Amazon to re-measure once new stock arrives.
What is length plus girth on Amazon?
Length plus girth is the longest side plus twice the sum of the median and shortest sides. Small bulky and large bulky items must be 130 inches or less on this measure, otherwise they move into the extra-large tier.
Why did my FBA fee go up when my product did not change?
Common causes are a re-measurement that put the item in a higher weight band or size tier, a price change that moved it into a different fee price band, the 3.5% fuel and logistics surcharge added in April 2026, or holiday peak fees from 15 October to 14 January.
Amazon fees, policies and features change often. Figures here were checked in October 2026; confirm current rates in Seller Central before making pricing or budget decisions. Sotrics is not affiliated with Amazon.