If you’ve just started an e-commerce business or are new to the shipping industry you may have heard the term dimensional weight and wondered what it meant. If you’re using a third party logistics company like Captech you won’t need to worry about all the details. But, if you’re shipping product yourself, you’ll probably want to understand how shipping costs are calculated. Dimensional weight is one factor in cost calculations.
What is Dimensional Weight?
Dimensional weight is a calculation most freight carriers use to account for the amount of space a package will take up on their truck or plane.
Historically, freight costs were determined only by the weight of the product. However, using this method, carriers realized that they weren’t taking into account the amount of space that the item consumed in their vehicles.
Imagine two boxes of the same size are shipped from point A to point B. If one of those boxes was full of feathers and the other full of rocks the shipping charges would be drastically different if they were only based on weight. Now imagine you have a delivery truck full only of the feather boxes and one truck full of the boxes of rocks. It may cost the shipping company about the same amount to transport and deliver the packages in each of the trucks but, one customer paid significantly more for shipping than the other.
Most shipping and freight companies added dimensional weight as a pricing factor to account for both the size and weight of the freight.
How Do You Calculate Dimensional Weight?
Dimensional weight calculations vary by company and can vary by destination. Here are few examples of how some companies are calculating dimensional weight currently.
- Please note that this information is accurate at the time this article was written. To get up to date accurate methods for determining pricing you should refer to each company’s website or customer support.
Measure Your Package’s Dimensions
For most calculations you will first need to take three measurements:
- Measure the longest portion of your package in inches. Do not use partial inches but round up to the nearest integer. This will be call L for length.
- Measure the widest portion of your package in inches. Do not use partial inches but round up to the nearest integer. This will be call W for width.
- Measure the shortest portion of your package in inches. Do not use partial inches but round up to the nearest integer. This will be call H for height.
Calculate Dim Weight
Now that we have our width (W), length (L) and height (H) we can calculate our dimensional weight using the appropriate formula below.
| Shipping Company | How is Dimensional Weight Calculated? | How is Shipping Cost Determined? |
| UPS (Domestic) | ( L x W x H ) / 139 (daily rates) ( L x W x H ) / 166 (retail rates) | Shipping cost is calculated using the larger of the dim weight and actual weight. |
| FedEx | (L x W x H) / 139 | Shipping cost is calculated using the larger of the dim weight and actual weight. |
| USPS (Select Rectangular Domestic Parcels) | L x W x H if the result is greater than 1,728 cubic inches then divide it by 166 and round up to the next whole number | Shipping cost is calculated using the larger of the dim weight and actual weight. If the dimensional weight is greater than 70, the customer pays the 70-lb price. |
| USPS (Select Non-Rectangular Domestic Parcels) | L x W x H (measured from their most extreme dimensions) * 0.785 if this result is greater than 1,728 cubic inches then divide by 166 and round up | Shipping cost is calculated using the larger of the dim weight and actual weight. If the dimensional weight is greater than 70, the customer pays the 70-lb price. |
More details can be found at each company’s website: