Dimensional weight, also known as DIM weight or volumetric weight, is a component of many carrier pricing structures which is designed to minimize the financial losses that would otherwise result from the handling of low-density parcels. While easily overlooked by those new to the eCommerce space, dimensional weight can materially impact expected shipping rates – oftentimes wrecking business models when it is either unanticipated or improperly estimated.  This post explores dimensional weight across the major carriers; its calculation; and ways to manage, minimize, and potentially eliminate it – all from our perspective as an eCommerce order fulfillment services provider.

Dimensional Weight Across Carriers

To calculate dimensional weight, carriers generally, though not always, divide the product of a package’s length, width, and height by a pre-determined DIM factor (which is designed to adjust for low-density). This quotient is then compared to the package’s actual weight and the higher of the two figures – either dimensional or actual – becomes the chargeable weight.  Below, the basics of dimensional weight are explored across several major carriers and service classes.

UPS and FedEx (Ground and Expedited)

With only a few exceptions, UPS and FedEx both apply dimensional weight to their ground and expedited shipments. The standard denominator utilized by both is 139; however, shippers with higher volume (tens of thousands of parcels per month and beyond) are sometimes able to negotiate denominators of either 166 or 194 – with higher denominators lowering dimensional weight.

United States Postal Service (First-Class and Priority)

The United States Postal Service (USPS) offers multiple service classes of which only some are currently subject to dimensional weight protocols. For parcels that are sent through USPS First-Class, dimensional weight does not apply; however, First-Class is only available for parcels weighing less than 16 ounces in actual weight.  Once a parcel reaches 16 ounces, it defaults to Priority Mail – a service class which does adjust for dimensional weight when package volume exceeds one cubic foot.  When applicable, USPS uses denominators of 166 for zones 1-4 and 194 for zones 5-8. 

Parcel Select (FedEx SmartPost, UPS SurePost, UPS Mail Innovations, and DHL eCommerce)

Depending on the carrier, parcel select offerings differ somewhat in their handling of dimensional weight.  FedEx SmartPost, for instance, applies dimensional weight the same way as FedEx Ground or other expedited service classes.  Both UPS SurePost and UPS Mail Innovations, however, have minimum weight and size thresholds before dimensional weight applies while DHL eCommerce uses a completely different calculation: adding a $1.50 per pound surcharge if a package either exceeds 50” in length + 2(width) + 2(height) or has a longest side which exceeds 27”.

A Real-World Ecommerce Order Fulfillment Example 

Consider, for instance, an eCommerce shipment with the following characteristics:

  • Contents: Three (3) large puffer jackets
  • Packaging: 14” x 12” x 12” corrugated carton
  • Destination: Portland, Oregon
  • Origin: Philadelphia, Pennsylvania
  • Actual Weight: 2 pounds
  • Dimensional Weight (139 DIM Factor): 15 pounds
  • Dimensional Weight (166 DIM Factor): 13 pounds
  • Dimensional Weight (194 DIM Factor): 11 pounds

Clearly, a low-density shipment like this has a very high dimensional weight relative to its actual weight, regardless of the denominator.  So, what would it cost to ship?

Absent dimensional weight, a two pound shipment like this could easily ship via USPS Priority at cost of $11.19.  Because the carton is slightly larger than one cubic foot, however, Priority will apply dimensional weight with a denominator of 194 – resulting in chargeable weight of 11 pounds and a cost of $41.67!

In this case though, the customer should actually shift to either UPS or FedEx Ground, assuming that the change in expected transit times is acceptable (USPS Priority generally delivers in 1-3 days while ground offerings usually deliver in 1-5 days).  With either carrier, however, base rates, residential and rural area surcharges, and fuel surcharges are likely to push the cost of shipping well above $15.00.

Managing, Minimizing, and Eliminating Dimensional Weight

Dimensional weight is a fact of life in the eCommerce space; however, there is quite a bit that can be done to manage, minimize, and (sometimes) eliminate it with a bit of planning.  A few possibilities:

  • Product Design – Consider dimensional weight as part of the product design process – tighten things up, if possible, when dimensional weight seems like it could apply.
  • Packaging Materials Design – Consider dimensional weight as part of the packaging materials design and/or selection process – use malleable, form-fitting materials, if possible, and even consider losing the unboxing experience in the interests of economy.
  • Volume Discounts – Negotiate with the carriers if volumes justify or consider pooling volume through either a third-party order fulfillment provider or shipping aggregator.


Understanding dimensional weight is critical for those in the eCommerce space. Without even a hint of hyperbole, shaving just an inch or two off of a parcel could make the difference between success and failure.