Dimensional Weight Explained

What is dimensional weight?


Dimensional weight also known as “Dim Weight” reflects package density, which is the amount of space a package occupies in relation to its actual weight. All shipments within the U.S., U.S. import-rated international shipments, and U.S. export shipments are subject to dimensional weight rating.

Dimensional weight has a direct impact on the billable weight used to calculate your shipping rate. For domestic and international services, the billable weight will either be the dimensional weight or the actual weight of your package (whichever is greater).

Why does dimensional weight make sense for the carrier?

In 2007, DHLFedEx, and United Parcel Service (UPS) implemented a dimensional weight system for ground services, where cubic size of package was greater than 12 in3. In May 2007, the United States Postal Service (USPS) adopted dimensional weight, calling it "Shape Based Postage Pricing". This rate system is designed to charge more for lightweight items that take up more space in planes and trucks, and also to recover costs for parcels that require manual sorting and handling. In 2015, FedEx and UPS moved to a system where all parcels were rated based on dimensional weight rather than just those greater than 12 in3. This change has enhanced the importance of understanding the dimensional weight concept.

How is dimensional weight calculated?

Dimensional weight is calculated based on the length, height, and width of the package. The dimensional weight becomes the billable weight when the dimensional weight of your package exceeds its actual weight.

Follow these easy steps to calculate dimensional weight:

  • Calculate the cubic size of your package in inches.Multiply the length by width by height of your package. Round each measurement to the nearest whole inch. The resulting total is the cubic size of your package.

  • Determine actual weight.Use any standard scale to determine the actual weight of your package. Increase any fraction to the next whole pound.

  • Determine dimensional weight.Divide the cubic size of your package in inches by 166 (for shipments within the U.S. and shipments between the U.S. and Puerto Rico) or 139 (for U.S. export and international shipments). Increase any fraction to the next whole pound.

  • Determine billable weight.Compare the package's actual weight to its dimensional weight. The larger of the two weights is the billable weight and should be used to calculate the rate.

  • For multiple-package shipments,total the billable weight of all packages in the shipment.

Examples of Calculating Dimensional Weight

Here are some examples to help you better understand how dimensional weight works for determining billable weight.

Riley Life Example:

We have a customer that uses a custom branded box to ship 1-2 men’s dress shirts. The dimensions of this box are 15” x 12” x 4”. The actual weight with 2 shirts inside the box is 2 lbs. However, based on use of dimensional weight, if the package was shipped domestically, it would ship at and be billed at 5 lbs. Thus, billable weight is 5 lbs.

15x12x4 = 720

720/166 = 4.33 (which would be rounded to 5 lbs.)

How are carrier and service class impacted by Dimensional Weight?

UPS and FedEx packages are typically ALL subject to dimensional weight. However, Riley Life has a waiver on FedEx SmartPost service to allow us to ship without concern for dimensional weight (with some restrictions for oversize items). Depending on what is shipped, this waiver can be a big deal.

USPS has publicly tried to scare customers into believing that they were an alternative to UPS and FedEx’s utilization of dimensional weight. In actuality, USPS is just a little more complicated with their approach to dimensional weight. They are a little more forgiving in their divisor (194) and how they apply their rate (primarily focused on packages traveling further distances). However, when using USPS Priority Mail, suffice it to say that while it is more complicated, overall the same mindset should apply in terms of there being increased costs for larger packages.

What is Riley Life doing to try to help me reduce my shipping costs associated with dimensional weight?

There are several things that Riley Life is doing to minimize the impact of dimensional weight and thus reduce your shipping costs. Here are a few:

  • FedEx SmartPost waiver – Parcels shipped from Riley Life using FedEx SmartPost service are priced based on actual weight and destination only, no dimensional weight factor

  • Stocking more box sizes – more box size options allow our packers to use the most precise size box possible to ship your item; no excess internal dimension is the easiest way to reduce the impact of dimensional weight across most service classes

  • Use of dimensional scanner to reduce additional charges being assessed later by the carrier as well as to eliminate human error of inputting dimensional weight on each shipment

  • Stocking box sizes based on what our customers ship most frequently – we capture and analyze the dimensions and quantities of ever unit of packaging material that leaves our facilities

  • Using higher quality boxes – using lighter but stronger packaging materials that don’t bulge or expand keeps dimensional weight captured downstream from increasing after a package leaves our facilities

  • Using protective wrap as appropriate but not in excess that causes box dimensions to needlessly rise

Feel free to call or message us if you have questions on how dimensional weight is impacting your shipping costs and how we can assist you in reducing this impact.


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