Dimensional Weight Calculator
Carriers do not bill the weight your scale shows: they bill the greater of that weight and the parcel’s volumetric weight. Enter your dimensions below to see which one you are paying for, and by how much.
The divisor depends on the service: Canada Post uses 5,000 for Xpresspost and 6,000 for Regular Parcel (cm/kg). Check your service and contract divisor.
Volume: 120,000 cm³. Carriers then round the billable weight up according to their rate card; this shows the value before rounding.
Source: Canada Post density factors
The formula
Billable weight = the greater of actual weight and volumetric weight
Example: a 60 × 50 × 40 cm carton holding 3 kg of goods occupies 120,000 cm³. Divided by 5,000 that is 24 kg of volumetric weight. The carrier bills 24 kg, not 3 kg: you pay for 21 kg of air, 88% of the billed weight.
This is the most profitable and most ignored saving in shipping: it is free, it acts immediately, and it applies to every future shipment rather than a single one.
To understand how that billable weight then becomes a price (zones, services, surcharges), see our Canada Post shipping rates guide.
Frequently asked questions
How is dimensional weight calculated?
Length × width × height (in cm) ÷ the carrier’s divisor. The divisor depends on the service: Canada Post uses 5,000 for Xpresspost and 6,000 for Regular Parcel, for example. The result is a weight in kilograms representing the space the parcel occupies.
What is the difference between actual and billable weight?
Actual weight is what the scale shows. Billable weight is the greater of actual and volumetric weight. That is what the carrier charges on. For a dense parcel the two match; for a bulky light parcel, volumetric wins.
Why does my small parcel cost so much to ship?
Almost always because its volumetric weight exceeds its actual weight: you are paying for volume, not mass. This is common with clothing, cushions, or a light product in an oversized box. Dropping one box size often moves the price band without changing the product at all.
Is the divisor the same at every carrier?
Canada Post uses 5,000 (cm/kg) for Priority, Xpresspost and expedited services, but 6,000 for Regular Parcel. Other services and contracts can differ. The divisor is contractual: if you hold a negotiated account, check which one applies to yours.
Does volumetric weight apply to every shipment?
It is calculated on every shipment, but it only changes the price when it exceeds actual weight. That is why a dense parcel is never penalised, while a light item in a large carton always is.