What Is Item Dimensional Weight on Amazon? How to Calculate It

What is Amazon dimensional weight?

Amazon uses dimensional weight (DIM weight) as a method to determine shipping costs based on an item's dimensions and its actual weight, taking into account the space the goods occupy during transport. Amazon calculates the shipping fee based on whichever is greater — the actual weight or the dimensional weight.

Why is this important to Amazon?

Amazon recognizes that larger but lightweight items may occupy substantial space, requiring higher shipping costs compared to compact, heavier items.

When is Amazon dimensional weight applied?

The dimensional weight calculation applies to Fulfilled by Amazon (FBA) orders, particularly for oversized parcels or items that consume a disproportionate amount of space relative to their actual weight.

Dimensional weight formula

DIM = (Length × Width × Height in inches) ÷ Divisor

For US shipments, the divisor is 139 (the US industry standard).

Example 1: Small-volume item

• Length: 12 inches
• Width: 8 inches
• Height: 6 inches
• Actual weight: 2 pounds

Calculation: (12 × 8 × 6) ÷ 139 = 4.68 pounds

Despite the 2-pound actual weight, shipping charges are based on the 4.68-pound dimensional weight.

Example 2: Large, light item

• Length: 20 inches
• Width: 20 inches
• Height: 4 inches
• Actual weight: 0.5 pounds

Calculation: (20 × 20 × 4) ÷ 139 = 5.76 pounds

Shipping costs are calculated using the 5.76-pound dimensional weight.

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