Volumetric Shipping is a calculation many shipping providers use to determine the billable weight of a package. It uses both the package’s weight and density to determine the costs needed to ship your item to its destination.
How it Works
Volumetric weight, also known as dimensional weight, is a calculated number based solely on the dimensions of the box you are shipping. It reflects the package’s density, which is the amount of the space a package occupies in relation to its actual weight. This number is generally calculated by dividing or multiplying the volume of the package by a special number given by your carrier. The image below, taken from the UPS website, illustrates how volumetric shipping works when sending packages within the United States.
The volumetric number here is 166. The dimensional weight is calculated by dividing the volume by this special number. Let’s say you are shipping a 12″ x 8″ x 8″ box. This box has a volume of 768 inches squared. Dividing that value by 166 results in a volumetric weight of 4.63 pounds.
The primary purpose of volumetric weight is to ensure that the shipping provider is compensated for both weight and size of the items being shipped. A box may be lightweight but large, which means it requires more space on the truck. In other scenarios, a box may be small but very heavy. To account for these situations, the calculated weight is compared to the physical weight of the box. The actual weight of the box is the greater of the two numbers.
Table Rate & Volumetric Shipping
The Table Rate shipping method is automatically setup to handle this with very little effort on your part. By entering a number into the Volumetric Number field you are enabling this calculation. By default the calculation is based on dividing the volume by this number. However some shipping providers use multiplication instead. The Operand box allows you to select which operator you need for the equation.
When enabled, the volumetric weight will be calculated for each item in the cart using the item’s dimensions. The calculated value will be compared to the entered weight given in the product’s settings. The higher of the two numbers will then be used as the item’s weight value. If you would prefer to always ignore the physical weight, this is possible with the Exclude Weight option.
Volumetric weight is considered the weight of an item, therefore your conditions in the table of rates should be weight to see its impact. The calculated ‘Volume’ will not change based on these settings so make sure you are using the correct conditions. The following tutorials are most commonly used in combination with volumetric shipping: