Dimensional DIM Weight Shipping Rates: What is it?

What is Dimensional ‘DIM’ Weight Rate pricing, and how do you calculate it?

United Parcel Service (UPS®), FEDEX®, The United States Postal Service (USPS®), and other package carriers charge what is known as ‘dimensional weight pricing’ for certain package sizes shipped using one, or more, of their service classes.

Note: Rates and calculations are subject to change at any time.  Consult your carriers’ rate tables for any updates.  (August 2007).

What is Dimensional Weight?

Dimensional weight rate is a calculation based on volume (the amount of space a package occupies in relation to its actual weight). If the volume exceeds a certain cubic inches, your billable weight rate typically is higher, not the actual weight of the package being shipped.

As of mid 2007, all major small-parcel carriers have applied this rate calculation to their ground shipping methods, where originally DIM weights only applied to their premium air shipments.

Note:  Package minimum weight, length of package, or class of service being used, and package size may also affect the price charged.  That amount may differ for DIM weight calculations. 

This DIM pricing method uses a simple formula, no matter what class of service, to determine the minimum charge you pay for a package.

Why does Dimensional Rate Weight shipping exist? 

When the carrier places your package on the plane or truck it uses up space, and space is a premium, especially if the truck weight limits are greater than the cargo they are carrying.  Their fixed costs are typically unchanged for the load size. Dimensional weight assures the carrier is getting paid properly for the space the packages actually take up on their trucks and airplanes.

The carriers want a better, more-precise way to charge mailers for carrying their goods.  So the space your packages take up in a carrier’s truck or plane will affect how they charge you.

This has become more important to carriers as fuel charges has increased, the density of shipping material has changed, and the type of cargo mix has changed.

Determining Dimensional Weight

Typically it is done like this: using the package’s Length (L), Width (W), and Height (H) measurements in inches, rounding up to the next full number for each measurement.  You multiply L x W x H to get a number that is the cubic inches of your package. 

For UPS and FEDEX Ground shipments to the US, if the cubic inches exceed 5184 inches (3 cu ft.), then dimensional weight rates will apply. (If the total cubic inches is under 5184 inches, then you typically use the actual rates for the weight of the package)

Once you have calculated the cubic size of your package and have determined that it is 5,184 cubic inches or greater, you are ready to calculate the dimensional weight. Divide the cubic size of your package by 194 (166 for ground shipments to Canada) rounding up to the nearest full pound.

Your billable weight will either the actual weight or dimensional weight of package, whichever is greater.

Domestic Ground Service 
L x W x H
194

Ground Service to Canada
L x W x H 
166

Examples of Calculating Dimensional Weight

Examples to help you better understand how dimensional weight works for determining billable weight.

Example 1: Actual package weight: 28 lbs.

Length (L): 30 inches
Width (W): 15 inches
Height (H): 15 inches

Cubic size calculation: 30 in x 15 in x 15 in = 6,750 cubic inches
Dimensional weight calculation: 6,750/194 = 35 lbs. Because the dimensional weight (35 lbs.) is greater than
actual weight (28 lbs.), 35 lbs. becomes the billable weight.

Example 2: Actual weight: 28 lbs.

Length (L): 35 inches
Width (W): 15 inches
Height (H): 8 inches

Cubic size calculation: 35" x 15" x 8" = 4,200 cubic inches
Because the cubic size in inches is less than 5,184,
dimensional weight does not apply. The actual weight
becomes the billable weight.

USPS Postal Service Dimensional Weight and Priority Mail

Note:  The USPS started applying a Dimensional Weight Pricing to their popular Priority Mail class of service in May 2007, when the rates for postage increased.  The pricing applies to ONLY boxes over 1-cu foot in size and also being delivered to Zone 5 or beyond.  (When you ship from your destination, you are always in zone 1.)

Determining DIM pricing for the USPS rectangular-shaped packages:

Calculate the cubic inches as above, and if that result exceeds 1,728, divide that number by 194 and round up.  That number is the DIM weight in pounds. See zone chart for destination, and if that destination is within zones 5 to 8, you pay the higher of the weight or DIM weight.

Zone charts from your zip code:

You can get a zone chart from your zip code here at the usps.com website following these pages:

Home > All Products & Services > Shipping & Mailing > 2-3 Day Packages > Priority Mail
or go to this URL: http://postcalc.usps.gov/Zonecharts/

Good News:  The Priority Mail-branded packages are all under 1-cu foot, including their flat-rate boxes.  Therefore, no dimensional weight rate shipping calculations are necessary for USPS Priority Mail shipments under 1 cu ft.

Get free ebay-branded Priority Mail Boxes starting at this ebay USPS shipping zone page: http://pages.ebay.com/usps/preparingitems.html