Dimensional weight, used in shipping and freight, is a billing technique which takes into account the XYZ axis dimensions of a package.
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Shipping costs have historically been calculated on the basis of gross weight in kilograms or pounds. By charging only by weight, lightweight, low density packages become unprofitable for freight carriers due to the amount of space they take up in the truck/aircraft/ship in proportion to their actual weight. The concept of Dimensional Weight has been adopted by the transportation industry worldwide as a uniform means of establishing a minimum charge for the cubic space a package occupies.
Dimensional weight is a calculation of a theoretical weight of a package. This theoretical weight is the weight of the package at a minimum density chosen by the freight carrier. If the package is below this minimum density, then the actual weight is irrelevant as the freight carrier will charge for the volume of the package as if it were of the chosen density (what the package would weigh at the minimum density). Furthermore, the volume used to calculate the Dimensional Weight may not be absolutely representative of the true volume of the package. The freight carrier will measure the longest dimension in each of the three axis (X,Y,Z) and use these measurements to determine the package volume. If the package is a right-angled rectangular cuboid (box), then this will be equal to the true volume of the package. However, if the package is of any other shape, then the calculation of volume will be more than the true volume of the package.
Dimensional weight is also known as DIM Weight, volumetric weight, Cubed Weight, etc. Freight carriers utilize the greater of the actual weight or dimensional weight to calculate shipping charges. Dimensional Weight is calculated as (Length x Width x Height) / (Dimensional Factor). Measurements can be made all in inches or all in centimeters, but the appropriate shipping factor must also be used.
Shipping factors for imperial measurements represent cubic inches per pound (in3/lb) while metric factors represent cubic centimeters per kilogram (cm3/kg). These are the inverse of the package density. Dimensional Weight is applied when the actual product density is less than the minimum density represented by the chosen factor. Dimensional Weight is representative of the weight of the package at the minimum density accepted by the freight carrier.[1] Shipping factors are not only different for imperial and metric measurements, but also for shipment mode and in some cases between different customers. Shipping factors will be available from your freight carrier. Some common factors are listed below.
Imperial Shipping Factor examples:
Metric Shipping Factor examples:
When calculating the dimensional weight with metric measurements, the Length, Width, and Height are measured in centimeters (cm) and the result is stated in a nominal kilogram (kg) dimensional weight band (usually rounded up).
Some Calculations for Major Courier/Shipping Companies are as follows:
(See external links for the DHL, FedEx, and UPS dimensional weight calculators)
Using dimensional weight calculations, a freight carrier will charge for lightweight (low density) packages as if they had a greater weight (the weight of the package at the minimum accepted density).
For example, a box of clothing shipped internationally which weighs 10 pounds, and measures 18 x 18 x 18 inches, would be charged as if it weighed 36 pounds: (18 x 18 x 18)/166 = 35.1 pounds which is then rounded up to 36 pounds. This is the weight the package would theoretically weigh if it had a density of 166 in3/lb or 10.4 lb/ft3. (18 x 18 x 18) = 3.375 ft3 x 10.4 lb/ft3 = 35.1 lb.
Several programs are available to calculate dimensional weight: Measurement Technology DIM Weight Calculator or Dim Weight Calculator
Dimensional weight favors shippers of dense objects and penalizes those who ship lightweight boxes. A box of unpopped corn kernels will likely be charged by gross weight; a box of popcorn will probably be charged by its dimensional weight. This is because the large box of popcorn takes up a lot of space but does not fill up a vehicle's capacity in terms of weight, making it an inefficient use of space.[5]
Shippers avoid dimensional weight charges by using smaller boxes, by compressing their goods, and by reducing the use of packing materials.
Dimensional weight is commonly used for invoicing by air freight forwarders, truck carriers, as well as all commercial airlines worldwide. In 2007, DHL, FedEx, United Parcel Service and USPS adopted the dimensional weight system for ground services.[6]
In May 2007, the United States Postal Service (USPS) adopted dimensional weight, calling it "Shape Based Postage Pricing". This rate system is designed to charge more for lightweight items, and also to recover costs involving manual sorting and handling, since many postal machines are built to handle flats. This system would charge much more for mailing a parcel than a flat envelope. It encourages mailing books and DVDs in flat paperboard or plastic envelopes, rather than padded mailers.[7]
Such companies use automated systems called dimensioners for calculating both dimensional and actual weight and invoice their customers accordingly. More and more transport and logistics companies including warehouses and retailers are investing in dimensioning equipment for calculating the dimensional weight of their packages in order to keep in line with their carriers and avoid back charges.[8]