Before you book, confirm the shipment’s packed dimensions, actual weight, and applicable DIM divisor, so your quote reflects the space your freight will use.
Dimensional weight is one reason a freight invoice may be higher than expected, especially when a shipment is large but lightweight.
A shipment does not have to be heavy to take up valuable space. If it occupies a large amount of space on a truck, aircraft, or carrier network, it may be rated by volume rather than actual scale weight.
In this article, we explain what dimensional weight is, how it is calculated, which shipments are most affected, and what you can do to reduce surprises on your next freight invoice.
Dimensional weight, also called volumetric weight, is a measure of how much space a shipment occupies. It is used to determine its chargeable weight.
A shipment has two weights that matter:
Carriers compare the shipment's actual weight to its dimensional weight. The higher number becomes the chargeable weight, which is then the weight used to calculate the freight charge.
Dense, compact freight is less likely to be affected because the actual weight often exceeds the dimensional weight.
Large, lightweight freight is more likely to be affected because dimensional pricing can create a noticeable difference between the quoted rate and the final invoice.
Dimensional weight is calculated by multiplying the shipment's length, width, and height, then dividing that volume by a dimensional factor, also known as a DIM divisor.
The basic calculation is:
Length × width × height ÷ DIM divisor = dimensional weight
Make sure you use the measurement units your carrier's divisor is set for, since an inch-based divisor and a centimetre-based one are not the same.
The DIM divisor varies by carrier, mode, service, and lane. Air freight, parcel, and other transportation services may all use different factors, so you should confirm the applicable divisor before relying on an estimated rate.
To estimate this for your own shipment, run the numbers through our dimensional weight calculator.
Dimensional weight applies most directly to parcel and air freight, where carriers routinely compare actual weight and dimensional weight, then bill based on the higher number.
Standard LTL (less-than-truckload) freight is usually priced by freight class rather than a straight actual-weight-versus-dimensional-weight comparison. However, dimensions can still affect the rate because freight class may consider factors such as density, handling, stowability, and liability.
Many LTL carriers also apply cubic-capacity rules that rate low-density shipments on the space they occupy, functioning much like dimensional weight. Density-based rating has become even more important with recent NMFC classification changes, which expanded its use for many LTL commodities.
FTL (full truckload) shipments are usually priced by the load, lane, or distance. Dimensional weight generally does not apply in the same way because you are typically paying for the trailer or dedicated capacity rather than a per-package chargeable weight.
Dimensional weight charges are not always avoidable, but they can often be reduced. Before you ship, review the following:
At Cole International, we offer trade consulting and freight forwarding services to help Canadian businesses move their goods efficiently and understand the full cost of every shipment.
Reach out to one of our trade professionals to discuss your shipment dimensions, freight charges, and ways to reduce invoice surprises before your cargo moves.