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Dimensional weight, or DIM weight, is a “weight” for shipping purposes based on the dimensions of the box rather than the actual weight on a scale. Every eCommerce company needs to understand dimensional weight to keep eCommerce shipping costs as low as possible. Your eCommerce fulfillment company can help you find creative ways to stay on top of the DIM weight. One technological solution is a dimensional weight scale.

dimensional weight

Understanding dimensional weight

Before we explore dimensional weighing, it’s essential to understand the concept of dimensions vs. weight. DIM pricing enables the carriers to include both factors that influence the cost to transport a package: weight and dimensions. A parcel that is lightweight but large represents an opportunity cost for the carrier because of the space it takes up in the truck. Dimensional pricing compensates for this.

DIM Weight v. Actual Weight

Carriers calculate both the actual and the dimensional weight and charge you for the greater of the two. Let’s say you have a package with dimensions of 12” x 12” x 12” that weighs 10 pounds. When you ship that package, USPS will charge you for the package’s actual weight, 10 pounds, but FedEx and UPS would record your package at 13 pounds — the DIM price.

Now imagine that 10-pound package in a smaller box that measures 10” x 10” x 10”. All three carriers would charge you for the actual weight because that is larger than the dimensional weight.

To unlock the mystery of dimensional weight pricing, we need to break it down a step further and look at the calculation that determines DIM weight.

Calculating length, width, and height to determine DIM weight

Dimensional weight uses this equation:

(L x W x H)/DIM factor = dimensional weight

The three main U.S. carriers — UPS, FedEx, and USPS — each have their own DIM factor. For 2021, FedEx and UPS both have a DIM factor of 139. USPS uses a DIM factor of 166. The higher the DIM factor, the lower the dimensional weight.

For our hypothetical package, shipped via FedEx or UPS, the dimensional calculation looks like this:

(12 x 15 x 12)/139 = 12.43 (rounded up to 13)

The USPS calculation is:

(12 x 12 x 12)/166 = 10.40

However, USPS only applies dimensional pricing on packages where L x W x H > 1,728. This package ships for its actual weight because its dimensions are a cubic foot or 1,728 square inches.

DIM weight example

To see how dimensional weight might affect your packages, use Red Stag Fulfillment’s handy dimensional weight calculator.

How does a dimensional weight scale work?

It’s important to know whether packages will ship for their actual weight or their dimensional weight. This can be challenging to calculate in a fast-paced order fulfillment setting. Some 3PL services companies use a scale that can measure dimensional weight while it records the actual weight of the parcel.

These weighing systems will often use lasers to detect the size of the box. In dimensioning systems, the scale transmits length, width, and height data, plus the weight in pounds, to software that calculates dimensional weight.

dimensional weight scale

Pros and cons of dimensional weighing

Dimensional weighing can quickly determine if you’ll incur DIM weight charges for your package. When integrated into eCommerce shipping operations, a dimensional weight scale can help you keep DIM costs in check by providing instantaneous feedback.

On the con side, dimensional weight scales can be finicky. If you don’t position your box correctly, you might get an incorrect measurement. Plus, while you might find a dimensioning system at a price point that your in-house fulfillment operations can afford, most are only economical for large-scale fulfillment warehouses.

The best argument against dimensional weighing is that there are better ways to calculate and control shipping costs. Here is what we do for our clients at Red Stag Fulfillment.

dimensional weight scale

4 ways Red Stag Fulfillment helps our clients reduce dimensional weight charges

When your pricing is based on the package dimensions, that can send shipping fees through the roof. If our 10-pound package were a little bit bigger, for example, the shipping costs would shoot up. At 15” x 15” x 15”, the DIM weight is 25 pounds for UPS and FedEx and 21 pounds for USPS. You’re paying for more than twice the parcel’s weight in pounds.

dimensional weight

Here are four of the ways Red Stag Fulfillment helps clients reduce dimensional weight charges.

  • Negotiated DIM factors. Red Stag Fulfillment is a high-volume shipper. That gives us leverage to negotiate favorable rates with each carrier, and we pass those discounted shipping rates on to our clients. Part of that negotiation is higher DIM factors to reduce dimensional shipping charges.
  • Optimized packaging. We work with our clients to find the perfect box for each order. By keeping the box size as close as possible to the actual product dimensions, we also reduce the infill needed, which also lowers the shipping weight and packaging cost. In most cases, packaging that fits products snugly will also reduce the chances of damage during transit because there is less room to move around.
  • Run the numbers. During our onboarding process, before we ever ship one package for you, we run the numbers to find the most cost-effective method for shipping your products safely. We factor in the weight of each item you sell and the dimensions of the boxes we will ship your orders in. Our approach is to plan ahead rather than relying on a dimensional weight scale at the packing station. That way, you can factor accurate shipping costs into every order.
  • Package consolidation. In some cases, consolidating several products into one package can save you money on shipping. When you combine a large item that falls into dimensional weight pricing with smaller items, the small items may ship for free because the actual weight is still less than the DIM weight. We also have freight shipment options that can deliver bulky items direct to your customer, often at a lower cost. After we run the numbers through our system, we’ll make recommendations about package consolidation.

Dimensional weight is complex, but there are ways to beat the math and reduce your shipping costs. Contact us to find out how Red Stag Fulfillment can help you save on shipping.

Master DIM weight today.