2010-01-04
Background
The courier and shipping industry in Canada, and around the world, often use a billing practice referred to as dimensional or volumetric weight in order to establish the shipping charge for delivering a package. You may notice dimensional weight entries on your invoice. Dimensional weight is a theoretical weight of a package based upon a minimum density or a conversion factor specified by the courier/delivery company. Dimensional weight is used to ensure that shipping charges adequately cover the cost of delivering lighter and/or bulkier packages.
The courier and shipping industry will determine both the weight and the linear dimensions of a package before calculating a shipping charge for the package. The dimensions of the package are used in a calculation to determine a dimensional weight value for the package. The dimensional weight value is then compared to the actual weight of the package. The charge is based upon the greater of the two values, actual weight and the dimensional weight value.
Some companies show the dimensional weight value on an invoice with a weight unit included (e.g. kg). However, dimensional weight is not a true weight and is not considered to be a unit of measurement. The unit of weight is not necessary, however, if one is used, the dimensional weight value must be accompanied by a qualifier such as a code, a dimensional weight statement, or by letters such as DIM or DW. The qualifier must make it clear to the customer that this value is in fact a dimensional weight value and not the actual weight of the package.
Calculations
Once the dimensions of a package are known, they are used in a calculation to produce a dimensional weight value. The calculation also uses a conversion factor specified by the delivery company. The results of the calculation will be used to determine which of the following methods will be used to calculate the charge for the package. When a package is heavy for its size (high density) and the actual weight of the package is larger than the dimensional weight value, the charge will be based upon the actual weight of the package.
When a package is light for its size (low density) and the actual weight of the package is smaller than the dimensional weight value, the charge will be based upon the dimensions of the package and the invoice will show a dimensional weight value.
Measurement Accuracy
Measurement Canada has deemed the use of dimensional weight statements as an industry billing practice and not as a unit of measurement. Billing practices are beyond the scope of the Weights and Measures Act; however, the actual measurement values (weight and dimensions) of a package must be accurate as prescribed by regulatory requirements. If inaccurate measurement is suspected, please contact the nearest Measurement Canada office.
Further Information
Full details about the methods and billing processes of delivery companies are usually provided on their websites. You are advised to review the information on these websites and if further information or clarification is needed, to contact a representative of the company that you are interested in.