DIM Weight Calculation: How to Calculate Dimensional Weight Pricing

One major factor in the pricing of shipments is dimensional weight. Whether you ship orders yourself or work with a third-party logistics (3PL) partner, you will likely encounter this pricing technique. Read on to learn more about dimensional weight and how it affects pricing.

What is dimensional weight?

Dimensional weight, also called DIM weight, is a pricing technique used for commercial freight transfer, including courier and postal services. Dimensional weight is computed by multiplying length times width times height.

Since the amount of space on a delivery truck is limited, dimensional weight takes into account package density to determine shipping rates. So even if you have a lightweight package, it could be worth it to calculate DIM.

Freight carriers like USPS, Fedex, or UPS calculate shipping charges based on whichever number is greater: the actual weight of the package or its calculated dimensional weight. Whichever is higher becomes your billable weight.

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How to calculate dimensional weight (DIM weight)?

To calculate dimensional (DIM) weight, multiply the length, width, and height of a package, using the longest point on each side. Then, divide the cubic size of the package in inches by the DIM divisor to calculate the dimensional weight in pounds.

Steps to calculate dimensional weight

1. Measure the length, width, and height of a package, using the longest point on each side. These measurements should take into account any bulges or misshapen sides, as irregularities can incur special handling fees if not incorporated into the initial calculations for dimensional weight.

2. When calculating dimensional weight, most shipping carriers request that you round up to the nearest whole number.

3. Next, multiply those package dimensions to get the cubic size of the package. For example, if your package is 30 inches by 12 inches by 12 inches, your package size is the product of these three measurements multiplied: 4,320 cubic inches.

4. Finally, the cubic size of the package is divided by a dimensional factor, also called a DIM divisor. DIM divisors are numbers set by the major freight carriers, such as UPS and FedEx. These factors represent cubic inches per pound.

The current DIM divisor used by FedEx, for example, for both domestic and international shipments is 139 cubic inches per pound. Using our example above, you would divide 4,320 by 139 to get a dimensional weight of 31 pounds. Here’s how a shipping carrier would charge for the package in this example:

  • If the actual weight of the package is less than 31 pounds (e.g., 29 pounds), the freight carrier will charge for the dimensional weight of 31 pounds since it is the greater number.
  • If the actual weight of the package is more than 31 pounds (e.g., 33 pounds), dimensional weight pricing will be based on the actual weight, not the dimensional weight, since they charge for the greater number.

We hope this article gives you some helpful insight into the world of shipping costs. If you’re uninterested in the hassles and expenses of self-fulfillment, you might need a 3PL. At ShipBob, we price our fulfillment services as simply and straightforwardly as possible with no hidden fees or nasty surprises when your bill arrives, and we negotiate and compare rates among all major carriers.

Want to know more about how ShipBob can help your business fulfill ecommerce orders and manage inventory? Request a quote today.

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Dimensional Weight FAQs

1. When do the revised dimensional weight calculations become effective?

In January 2017, FedEx and UPS changed their dimensional weight rules. FedEx changed dimensional weight divisor from 166 to 139 for domestic shipments. For packages that are over one cubic foot in size, UPS will also have a dimensional weight divisor of 139. If the package is less than one cubic foot, UPS will use 166 as the divisor.

2. What is volumetric weight and how is it calculated?

Volumetric weight is an alternative term for dimensional weight. Like DIM weight, it is calculated by multiplying the length, width, and height of a package, then dividing by a DIM divisor to calculate the dimensional weight in pounds.Freight carriers utilize the higher weight between actual weight and volumetric weight to calculate shipping costs.

3. How does FedEx calculate dimensional weight?

FedEx calculates dimensional weight for both domestic and international shipments by dividing the cubic size of a package by a DIM divisor of 139. If the dimensional weight is higher than the actual weight, then FedEx charges for shipping based on the dimensional weight.

4. How do you calculate dimensional weight in pounds?

Dimensional weight in pounds can be calculated by dividing the cubic size of a package in inches by a dimensional factor or DIM divisor  — often 139 or 166, depending on the carrier and destination.

5. When do I need to think about dimensional weight?

It’s important to keep dimensional weight in mind when choosing which boxes to ship your products in. Larger boxes will lead to larger DIM weights, which in turn will lead to more expensive shipping costs. Use the smallest box possible while still ensuring orders are shipping securely and leaving enough room for any necessary air fill, bubble wrap, and other types of dunnage.