Definition  Dimensional weight is a calculation of the volumetric weight of a package, using the package’s length, width and height. 
Using this article  Dimensional weight is used to determine your item’s product size tier and shipping weight in certain instances. After reading this article, you will be able to (1) determine whether dimensional weight is used to calculate fees for your item and (2) calculate the dimensional weight for your product. To accomplish these tasks, you should first know the unit weight, product volume, and product dimensions. 
Fees that use this attribute 
Monthly inventory storage fees FBA inventory storage overage fees Fulfillment fees for MultiChannel Fulfillment orders 
Related terms and articles 
Dimensional weight is calculated using your item package’s dimensions. To calculate dimensional weight, multiply the package’s overall length, width, and height, then divide by 139. For more information, go to the Calculate dimensional weight section below.
Dimensional weight may apply when calculating fees for items that meet any of the following criteria:
Use the dimensions and unit weight to determine if the item is standardsize or oversize.
A small standardsize item meets all of the following criteria when fully packaged:
A large standardsize item is not small standardsize and meets all of the following criteria when fully packaged:
Items that do not meet the standardsize criteria above are considered oversize. A special oversize tier applies to products that must be delivered using special delivery options due to their size, weight, special handling requirements, or other restrictions. Products are classified and charged as special oversize if any of the following is true:
If your oversize item did not meet any of these criteria, the greater of dimensional weight or unit weight is used to calculate fees. If it does meet any of the criteria, the item is considered special oversize, and only unit weight is used instead.
The dimensional weight is equal to the unit volume (length x width x height) divided by 139. The dimensional weight for oversize items assumes a minimum width and height of 2 inches.
You can look up product dimensions for your existing FBA inventory using the Monthly Storage Fees report. To do so:
For products that are already being sold in Amazon stores but you do not sell, you can look up the product dimensions to calculate volume by using the Revenue Calculator. To do so:
For products you currently have in FBA inventory, you can look up the size tier using the Fee Preview report. To do so:
Dimensional weight with a 2 inch minimum  


White dry erase board
Dimensions: 40 x 1 x 25 inches Unit weight: 4.5 lb Dimensional weight: 14.4 lb, 2inch minimum applied (40 x 2 x 25 inches, divided by 139) Item is oversized, but not special oversized, so dimensional weight is used for fee calculations. 
The measurement system for product dimensions and volume vary depending on the local standard in which the fees are calculated. The fee Help content for the region indicates which measurement system and units of measure are used for that region.
How is unit weight different from dimensional weight?
Unit weight is the scale weight of the product when fully packaged. Dimensional weight is an estimate of what the weight will be based on the product’s dimensions. Depending on the size tier of the product, either the unit weight or the dimensional weight will be used to calculate the shipping weight. View more details on the Shipping weight page.