The cost of shipping an item is calculated using its size and weight. Rectangular or square parcels, and bundles of newspapers, magazines or catalogues are measured by determining length, width, height or girth, as applicable.
Volumetric weight is charged when items of any shape are large in size and light in weight. The shipping price is based on the greater of the volumetric weight or the actual weight.
To determine if an item meets volumetric weight requirements and to calculate the correct postage, please follow this procedure:
 Determine the volume  Find the volume using the largest facing surfaces, length is the longest dimension and width the shortest. Height is measured at right angles to the largest surface. Girth is the distance around the item, measured at right angles to the length. These measurements are shown in Figure 7.
For a square, rectangular or mailing tube, calculate the volume by multiplying:
length (A) x width (B) x height (C). For an oddshaped nonrectangular item, measurements are taken at the widest points.
Figure 7:
 Determine the volumetric weight  Calculate the item's volumetric equivalent of its actual weight by dividing its cube, or cubic volume, as measured in Step 1 by the density factor.
 The formula we use to calculate the volumetric equivalent of the item's actual weight is
 Cubic volume ÷ density factor = volumetric equivalent actual weight.
 The density factor is a number that reflects the fact that items weighing a certain amount are generally of a certain size or volume:
 We apply a density factor of 5,000 (when measuring in cubic centimetres) or 139 (when measuring in cubic inches) to Priority, Xpresspost and Expedited services, as well as all U.S. and international services (excluding Tracked Packet and Small Packet)
 We apply a density factor of 6,000 (when measuring in cubic centimetres) or 166 (when measuring in cubic inches) for the Regular Parcel service
For the volumetric weight in pounds, divide the volume of the item (in cubic inches, as calculated in step 1) by a cubing factor of 139 or 166 cubic inches depending on service used (see above).
 Determine the actual weight  Weigh the item to determine it’s actual weight in lb. or kg.
 Determine the shipping price The shipping price is calculated using the greater of the volumetric weight or the actual weight. The actual weight cannot exceed 30 kg.
NOTE: A surcharge will be applied to mailing tubes that are cylindrical in shape. Cylinder shaped packages generate high processing costs due to their unique shape. Customers are encouraged to use other noncylinder shaped containers (e.g. triangular shape) to avoid the surcharge.
Example Calculation of Weight vs. Volumetric Weight
In the following example, an Xpresspost item measures 100 cm x 60 cm x 40 cm and weighs 22.7 kg.
Length (A)  x  Width (B)  x  Height (C)  =  (volume) 
100 cm  x  60 cm  x  40 cm  =  240,000 cm^{3} 
240,000 divided by 5,000 = 48 kg (volumetric weight) 
The volumetric weight is greater than the actual weight. Therefore, the shipping charge will be based on the volumetric weight of 48 kg.
NOTE: The Customer is responsible for submitting to Canada Post accurate measurements for each item for rating purposes. The measurements submitted on the Bill of Lading or on the electronic or hard copy of the manifest will be the greater of the actual weight or volumetric weight. The item may be reweighed and cubed by Canada Post (or FedEx, in the case of Priority™ Worldwide items). Reweighing and cubing are done on governmentapproved equipment. When an item is cubed, the dimensions provided are the dimensions of the smallest hexahedron* within which the item can be contained. When Canada Post detects that an item’s actual or volumetric weight as declared by the Customer is different than the actual or volumetric weight, the Customer’s invoice will be adjusted as applicable. When no weight is indicated on the shipping documentation and the item is not reweighed by Canada Post, Canada Post reserves the right to charge a default weight of 5 kg (11 lbs) that applies to each item shipped by any service. For rating purposes, an item weighing less than 750 g will be rounded up to 750 g; an item weighing more than 750 g is rounded up to the nearest half kilogram. If the dimensions and weight of any returned parcel cannot be determined, Canada Post reserves the right to charge based on a default weight of 1 kg for Domestic Parcel Services and 750 g for prepaid envelopes and labels.
* A hexahedron is a geometric solid or box consisting of six plane rectangular sides
