Packed box
Divisor
Based on Amazon US FBA rules for 2026. Amazon’s own measurement of your packed unit is final.
How Amazon dimensional weight works
Dimensional weight
L × W × H (in) ÷ 139A 16 × 12 × 8 in box has a dim weight of 1,536 ÷ 139 = 11.05 lb, even if the item inside weighs 1.4 lb.
Shipping weight
max(unit weight, dim weight)Used for large standard, small bulky, large bulky and extra-large items up to 150 lb. Small standard and items over 150 lb use unit weight only.
2-inch minimum
For small bulky, large bulky and extra-large items, Amazon counts width and height as at least 2 in when it works out dim weight.
Frequently asked questions
What is the dimensional weight divisor for Amazon FBA?
139 for Amazon US, with sizes in inches and weight in pounds. UK and EU marketplaces use 5,000 with centimeters and kilograms.
Does dim weight apply to small standard items?
No. Small standard items (up to 15 × 12 × 0.75 in and 16 oz) are billed on unit weight only.
How do I lower my dimensional weight?
Use a box that fits the product closely, remove empty space, and compress soft goods. Even 1 in off each side can cut dim weight a lot.