Understanding Dimensional Weight & DIM FACTOR

                 The Importance of Volume and Weight of Cargo for Transportation

All cargo space involved in transporting goods has physical limits based on the volume of the cargo and the weight.   Once a cargo has reached a limit in either volume or weight – the container (trailer, train, plane or shipping container) is transported.  Weight has traditionally been the measurement that the transportation costs of individual packaged freight have been calculated.

The difference in weight and volume costs can be appreciated if one considered the expense of transporting a large volume with little weight (e.g. large boxes of Styrofoam drinking cups).  Transportation companies have recognized these variables and most have allocated a volume per weight standard in their billing to capture cargo of light density. 

Dimensional (Volume) Weight

The dimensional weight (also known as volume weight) is the minimum weight that a package a given size may have that is handled by a carrier.  A carrier may state that any package of one cubic foot (12”x12”x12”) will have a minimum weight allowance of 10 pounds.  If the cubic foot package actually weighs 8 pounds – it will be invoiced for 10 pounds.  This is a minimum weight allowance – if the cubic foot package weighs 12 pounds – the charges will be based on 12 pounds.

? There are no international or domestic standards concerning values of dimensional weight covering all modes of transport.  A significant number of courier companies use the dimensional weight standard set by the International Air Transport Association (IATA) but many regional couriers define their own dimensional weights for ground delivery.

In the US as in other countries, the IATA standards have come under increased scrutiny as ‘clearly a price-fixing agreement among horizontal competitors’ ¹.  If the US Department of Justice recommendation was followed, the Department of Transport would withdraw the approval and antitrust immunity for all IATA agreements and members would set their own low-density formulas (DIM Factors) in a free market environment.  In this competitive environment, it will be much more critical for shippers to know the DIM FACTOR used by their carrier.

¹Docket OST-2003-14480 submission by Antitrust Division, U.S. Department of Justice concerning a request from IATA to lower the DIM Factor (Resolution 502)

DIM Factor (Dimensional Weight Factor)

The DIM Factor is a mathematical factor used to calculate the dimensional weight of an object.  The DIM Factor represents the volume of a package allowed per unit of weight.  Although mathematically related, the DIM Factor is different for measurements in units of inches/pounds and for measurements in centimeters/ kilograms.

All major courier companies now apply the DIM Factor to virtually every cuboidal (rectangular/ square) parcel that they handle to determine the dimensional weight.  They then adjust customer invoicing to reflect charges based on the greater weight between actual weight and dimensional weight.

Finding a DIM Factor using in/lb

Find the DIM factor if each cubic foot (12”x12”x12”) has a minimum weight allowance of 10 pounds:

Finding a DIM Factor using cm/kg

Find DIM factor if each cubic meter (100cm x 100cm x 100cm) has a minimum weight allowance of 200 kg:

IATA Dim Factors

Currently used by most large North American couriers:

            Domestic        =          Dim Factor [in³/lb] = 194

International            =          Dim Factor [in³/lb] = 166 ; [cm³/kg] =6000

        International (Proposed) =          Dim Factor [in³/lb] = 138 ; [cm³/kg] =5000