How to Calculate Dimensional Weight for Shipping

Jul 2020
Nikolay Pasholok
Product Owner, Calcurates
If you have ever tried to use a shipping weight calculator, you have probably noticed that the estimate often doesn’t represent the actual weight of the package. That’s because carriers usually apply dimensional weight (also called DIM or volumetric weight), which is not a precise measure but a pricing technique.

What is Dimensional Weight?

Shipping companies calculate dimensional weight — an abstract variable based on the length, width, and height of the package, which makes their business more cost-effective. Carriers began using this pricing method when charging clients for actual weight became unprofitable. Lightweight yet low-density shipments took up considerable space but brought no profits because of their cheapness.

To unify the pricing principles, carriers introduced dimensional weight; however, each company reserved the right to use its own density minimum (one of the variables of the DIM weight). Before 2015, dimensional weight was only used for packages over a specific size, but now it is a standard pricing method across all top-tier shipping providers.

How to Calculate Dimensional Weight?

To calculate the dimensional weight of your package, first, you need to measure its length, width, and height. For right-angled boxes, the process is straightforward, and the DIM weight corresponds with the real volume of the package. When dealing with any other shape, the figure you’ll get will be greater than the actual weight.

Then, apply the dimensional weight formula:

(length × width × height) / shipping factor

The shipping factor (or DIM factor) is a special variable different for every carrier. It represents the value of minimal density, chosen by the shipping company as a DIM divisor in the formula. This value is estimated in cubic inches per pound or cubic centimeters per kilogram for the imperial and metric systems, respectively.

Remember that when the actual weight exceeds the volumetric one, the carrier applies the greater value for the shipping price. Compare the dimensional weight that you got from the formula with the package’s actual weight to determine the value that will be used by the carrier.

As the shipping factor varies from carrier to carrier, the volumetric weight of the package will be different as well. It is better to double-check with carriers’ official websites to ensure that the DIM divisor is correct. Note that while major carriers use dimensional weight universally, smaller companies use cubic size as the primary pricing factor.

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Calculating Dimensional Weight with FedEx

FedEx has implemented the dimensional weight pricing technique across all its services. Unlike many other carriers, FedEx has one shipping factor. To calculate the DIM weight for a FedEx parcel, put 139 cu in/lb (or 5000 cm3/kg for the metric system) into the aforementioned dimensional weight formula. Use the dimensional weight calculator on the FedEx website.

Calculating the Dimensional Weight with USPS

USPS has been using volumetric weight since 2007. They call it shape-based postal pricing.

For the Global Express Guaranteed shipping option, USPS applies the International Air Transport Association (IATA) standard DIM factor of 166 cu in/lb (or 6000 cm3/kg for the metric system).

When shipping domestically through Priority Mail to Zones 5–9, put 194 cu in/lb (7000 cm3/kg) into the dimensional weight formula. USPS uses DIM weight only for parcels over 1 cubic foot/1,728 cu in.

There is no USPS dimensional weight calculator online — estimate it manually or set up Calcurates to automate the routine.

Calculating the Dimensional Weight with UPS

The carrier uses two DIM factors to calculate the volumetric weight but applies this approach only to particular services.

UPS uses 139 cu in/lb (5000 cm3/kg) for:
  • All international shipments
  • Daily rates for parcels exceeding one cubic foot and shipping domestically
  • All Canadian domestic packages except for the UPS Standard option
The 166 cu in/lb (6000 cm3/kg) shipping factor is used for:
  • Daily rates for parcels less than or equal to one cu ft. shipping domestically
  • Retail rates for parcels shipping locally
  • Canada domestic parcels using the UPS Standard option

In the absence of a UPS dimensional weight calculator, you will have to determine the volumetric weight of every shipment manually or with the help of Calcurates.

Calculating Dimensional Weights with DHL Express

DHL uses volumetric weights across all its services with a single DIM factor of 139 cu in/lb (5000 cm3/kg). For packages shipping to the United Arab Emirates, however, the shipping factor is lower — 111 cu in/lb (4000 cm3/kg). Use the DHL dimensional weight calculator to get accurate results.

Automating DIM Weight Calculations with Calcurates

If you want to accurately estimate the shipping rates for the products you sell, it is essential to know the volumetric weight of every item. Otherwise, you run the risk of presenting incorrect shipping costs to your customers. Calcurates can help you out with this.

Stock versions of the Magento e-commerce platform don’t enable you to automatically measure dimensional weights. Calcurates does: Just fill in the shipping factor for the carrier you use once, and the extension will take care of the rest. Calcurates uses pre-set sizes of each product to calculate the dimensional weight and offer accurate prices.

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