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Parcel dimensional weight and pricing have become standard in the shipping industry. But, many shippers continue to fret over how dimensional pricing (DIM Pricing) will impact their bottom lines. To the untrained eye, DIM pricing looks like another way for carriers to get more money from shippers, and with carriers changing DIM weight factors every few years, the suspicion grows stronger. However, DIM pricing is not a fad or something to fear if you know what it means and how to calculate it. So, let’s look into DIM weight and what it means for your company.

What Is Parcel Dimensional Weight?

Parcel dimensional weight refers to the calculation of a package’s volumized weight, otherwise known as its cubic weight. Part of the reason carriers started using it derives from shippers sending low-weight packages in bulky boxes and excess packaging. For carriers, this amounts to lost opportunities and underutilized space during shipping. Thererfore, carriers calculate the volume of a shipment and divide it by a parcel dimensional weight factor, which may vary by carrier. The resulting weight is different from a package’s actual weight.

Why Do You Need to Know Its Actual Weight Too?

Shippers still need to know a package’s actual weight. After calculating the parcel dimensional weight of a shipment, it is compared against a package’s actual weight. The higher weight of the two results is the weight the carrier uses when determining shipping costs.

For example, a package with an actual weight of 11 pounds and a parcel dimensional weight of 20 pounds will be shipped using the 20-pound weight.

Can Companies Opt to Bill You Differently?

Carriers have the option of billing you differently for DIM weight versus actual weight, based on the terms of the agreement or contract you enter. But, new shippers to the carriers are not likely to have access to these benefits. This is why more shippers are looking to carriers as a partner, not just an afterthought and expense.

If a shipper wants to avoid DIM weight, he or she should express these views during contract negotiation. Even if the carrier refuses, at least the shipper had the opportunity to ask and make his views known. But, DIM weight brings up another problem. What happens if a package is odd-shaped or very long?

What About Packages That Have Odd Shapes?

Packages with odd shapes still require the volume calculation. Volume is calculated with this formula:

Length x Width x Height = Volume.

Depending on the carrier, items shipped in cylinder-like packages may be calculated using a slight variation that requires a square-like assumption of the package.

For example, a cylinder with a diameter of 10 inches would replace both the width and height in the equation. The length remains the same.

For example, 10 inches x 10 inches x length (using 10 in the example) would produce a result of 1,000.

Dividing 1,000 by the DIM weight factor of 138.4 results in an DIM weight of 7.23 pounds. However, all DIM weights are rounded up to the nearest pound. So, the DIM weight is 8 pounds.

However, this may seem incorrect as the volume of cylinder is traditionally calculated by multiplying the circle-end’s area by the length. As of today, neither UPS nor DHL calculate the DIM weight of cylinder-like packages with this mathematical formula. The diameter of the cylinder is used in place of both height and width. But, why do carriers not use the traditional formula for calculating volume of cylinders? Consider this example.

The formula for calculating area of circle traditionally is as follows:

πrx length.

Rather than trying to remember the decimal number of π, here is the formula broken into its steps.  

Diameter / 2 = Radius (r).

Radius x Radius = r2.

π = (22/7).

rx (22/7).

So, let’s plug in a package with a 10-inch diameter and a 10-inch length.

10/2 = 5.

5 x 5 = 25.

25 x (22/7) = 78.5714 (Area of the cylinder at one end).

78.5714*10 = 785.714 cubic inches.

Now, divide the cubic inches by the DIM weight factor (138.4) .

785.714 / 138.4 = 5.677 pounds.

Now, the formula most commonly used would have 10-inches for the width, 10 inches for the height and 10 inches for the length.

10 x 10 x 10 = 1,000 cubic inches.

1,000 / 138.4 = 7.225.

Rounding 7.225 up results in a DIM weight of 8.

Using the width x height x length calculation for odd-shaped packages would have a higher result of 7.22. So, the standard calculation package’s DIM weight is 8 pounds, not 6 pounds.  

Know Your Carrier’s DIM Weight Factor.

Another thing shippers need to know is the DIM weight factor for the carrier selected. For UPS, DHL and FedEx, the DIM weight factor for domestic or ground shipments is 138.4, reflecting a decrease that took effect at the start of 2017. International and air shipments use 166 as the DIM weight factor.

Using the 10-inch example, the result would be slightly less for air or international shipments.

10 x 10 x 10 = 1,000.

1,000 / 166 = 6.02.

Round 6.02 up.

DIM weight is 7 pounds.

What Else Do You Need to Consider?

Packages using DIM weight may be subject to a surcharge if any dimension exceeds a certain length.

For example, a package’s height plus its width exceeds a set length. UPS considers all sides as well. So, double the length, and double the width first. Add them together. If total is more than 129.921 inches, it is subject to a minimum weight charge of 89 pounds. Let’s look at the example real quick.

2 x 10 (width) = 20.

2 x 10 (height) = 20.

20 + 20 = 40 inches.

Since 40 inches is less than 129.921 inches, it is not subject to this rule. But, a package with a larger height, like 60 inches, is.

2 x 10 (width) = 20.

2 x 60 (height) = 120.

120 + 20 = 140 inches.

This is higher than the 129.921, so the billable automatically has an 80-pound minimum.

Figuring out your shipment’s DIM weight can be confusing, and do not be afraid to use your calculator to figure it out. By understanding DIM weight and breaking it down, you can change your packaging practices to avoid extensive surcharges and reduce your shipping costs.

If you still do not understand, most carriers have a DIM pricing calculator available online, like this one from DHL.

Play with it, check it out, and you will see how DIM weight changes with changing dimensions.