About the Dimensional Weight Calculator
This dimensional weight calculator works out a parcel's billable shipping weight the way courier and freight carriers actually charge: by comparing the parcel's actual weight against a volumetric weight calculated from its dimensions, and billing whichever figure is higher. It answers the question that catches people out when shipping something light but bulky — why a nearly-empty box can cost as much to send as one packed full.
How to use the Dimensional Weight Calculator
- 1
Enter the parcel's length, width and height in centimetres.
- 2
Enter its actual weight in kilograms.
- 3
Choose the carrier's divisor — check your specific carrier's published rate, since this varies.
- 4
Read the billable weight, and which figure — actual or volumetric — it was based on.
What people use it for
Quoting a shipping cost before packing
Estimate the billable weight before finalising packaging, so a shipping cost isn't a surprise once the parcel reaches the courier's counter.
Choosing the right box size
Compare the volumetric weight of two candidate box sizes to see which keeps the shipment on the cheaper, weight-based side of the calculation.
Understanding an unexpectedly high shipping bill
Work out whether an invoice was based on actual or volumetric weight, and by how much, when a shipping charge looks higher than expected for a light item.
Why carriers bill by volume as well as weight
A cargo plane or delivery van has a fixed amount of physical space and a fixed weight capacity, and either one can run out first. A large, light parcel — an inflatable, a lampshade, a box padded out with packing material — can fill space that would otherwise carry several heavier parcels, so if carriers only charged by actual weight, low-density shipments would be effectively subsidised by everyone else's. Volumetric weight exists to reflect the real cost of the space a parcel occupies, not just what it weighs on a scale.
Reading a carrier's published divisor
The divisor converts a parcel's volume in cubic centimetres into an equivalent weight in kilograms, and it encodes an assumed average shipment density for that specific carrier and service — 5000 is common for many international couriers, though some express and air freight services use a smaller divisor such as 4000, which produces a higher volumetric weight for the same box. Always check the specific service being used rather than assuming one standard figure, since the difference can be significant for a large, light parcel.
Tips
- Measure to the outer dimensions of the packed box, including any padding, not the product inside it.
- A smaller divisor means a higher volumetric weight for the same box — check which direction your carrier's specific figure works before assuming a bigger number is worse.
- For a genuinely light, bulky item, a smaller box with tighter, more efficient packing directly lowers the volumetric weight and the shipping cost with it.