Overview

Dimensional weight is a pricing technique that uses a package's physical dimensions—rather than just its actual weight—to calculate shipping and fulfillment costs. For Amazon FBA sellers, understanding how dimensional weight works is essential because it directly influences the fees you pay on every unit stored and shipped through Amazon's fulfillment network.

Key Points / What Sellers Need to Know

• Dimensional weight may override actual weight – Amazon compares your product's actual unit weight against its calculated dimensional weight, and in many cases uses the greater of the two when determining fees. This means a lightweight but bulky item could cost significantly more to fulfill than you might expect.
• It determines your product size tier – Amazon uses dimensional weight as one of the factors in classifying products into size tiers (standard-size vs. oversize), which carry very different fee structures.
• Multiple fee types are affected – Dimensional weight impacts FBA fulfillment fees, removal order fees, disposal order fees, and inbound placement service fees. A miscalculation can ripple across several cost categories.
• You need three measurements to calculate it – To determine dimensional weight, you must know your product's length, width, and height. Combined with unit weight and product volume, these figures let you predict which fee tier your item falls into.
• Optimizing packaging can reduce costs – Since dimensional weight is based on package dimensions, reducing unnecessary空間 in your packaging can directly lower your fulfillment expenses.

How Dimensional Weight Is Calculated

Amazon calculates dimensional weight by multiplying a package's length, width, and height to determine its volume, then dividing by a standard dimensional factor. The result is compared against the item's actual unit weight, and the higher value is used as the "shipping weight" for fee calculations. This approach ensures that large but lightweight products—such as pillows, pet beds, or oversized toys—are priced in a way that reflects the space they occupy in fulfillment centers and delivery vehicles rather than just how much they weigh on a scale. Sellers should measure their products carefully using the outer dimensions of the fully packaged item, as Amazon will verify measurements and may adjust them if discrepancies are found.