Dimensional weight
| 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 Multi-Channel Fulfillment orders |
| Related terms and articles |
Determine if dimensional weight is used to calculate fees
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:
- The item is non-apparel and large standard-size; or
- The item is apparel and weighs more than 0.75 pounds; or
- The item is oversize, but not considered special oversize.
Use the dimensions and unit weight to determine if the item is standard-size or oversize.
A small standard-size item meets all of the following criteria when fully packaged:
- Unit weight is less than or equal to 1 pound
- Longest side (length) is less than or equal to 15 inches
- Median side (width) is less than or equal to 12 inches
- Shortest side (height) is less than or equal to 0.75 inches
A large standard-size item is not small standard-size and meets all of the following criteria when fully packaged:
- Unit weight is less than or equal to 20 pounds
- Longest side (length) is less than or equal to 18 inches
- Median side (width) is less than or equal to 14 inches
- Shortest side (height) is less than or equal to 8 inches
Items that do not meet the standard-size 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:
- Unit weight is greater than 150 pounds
- Longest side (length) is greater than 108 inches
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Girth plus length is greater than 165 inches. To calculate girth plus length:
- Measure the length, height, and width of the packaged unit.
- Calculate the girth by adding the shortest and median sides and multiplying by 2.
- Add the longest side and girth.
- Amazon has determined that the product requires special handling to ensure a good customer experience
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.
Calculate dimensional weight
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:
- Download the report
- Identify the product of interested by its FNSKU
- View the Product dimensions in the longest-side, median-side, and shortest-side fields
- Use the formula above to calculate the product volume and convert to dimensional weight
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:
- Search for the product of interest
- View the Package Dimensions values
- Use the formula above to calculate the product volume and convert to dimensional weight
For products you currently have in FBA inventory, you can look up the size tier using the Fee Preview report. To do so:
- Download the report
- Identify the product of interested by its FNSKU
- View the product size tier in the product-size-tier field
Dimensional weight example
| Dimensional weight with a 2 inch minimum | |
|---|---|
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White dry erase board
Dimensions: 40 x 1 x 25 inches Unit weight: 4.5 lb Dimensional weight: 14.4 lb, 2-inch 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. |
Frequently asked questions
Which measurement system does Amazon use to measure products and calculate fees, imperial or metric?
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.
