Enter a package's weight and dimensions to see whether your courier bills you by actual weight or dimensional weight, and estimate the shipping cost either way.
Spend less time on manual content creation. VidyBack auto-generates and schedules product videos straight from your Shopify catalog, so every SKU gets seen, not just the bestsellers.
See How VidyBack WorksDimensional (or volumetric) weight is a courier's way of billing for the space a package takes up, not just how heavy it is. A truck or cargo plane has limited volume, not just a limited weight capacity, so carriers calculate an "equivalent weight" from a box's dimensions and charge whichever number is higher: the actual weight on a scale, or the dimensional weight from its size. This is why a large, lightweight box can cost as much to ship as a small, dense one.
Sellers are frequently caught off guard by this. A product that feels light in your hands, like a lampshade, a pillow, or anything packed with a lot of void fill, can rack up a dimensional weight several times its actual weight, and that's the number your courier bills against.
Worked example: A box measuring 40 × 30 × 20 cm weighs 2 kg on a scale.
Dimensional weight = (40 × 30 × 20) ÷ 5000 = 4.8 kg
Since 4.8 kg > 2 kg, the courier bills you for 4.8 kg, not the 2 kg the package actually weighs.
That gap, 2.8 kg of "invisible" weight, is pure packaging inefficiency. Sizing boxes tighter to the product is often the single cheapest lever a store has to cut shipping costs.
The divisor your carrier uses depends on their service and unit system. Always confirm the exact figure in your own rate card, but as a general reference:
| Divisor | Typically Used By | Units |
|---|---|---|
| 5000 | Most international couriers (DHL, FedEx Intl, UPS Intl) | cm / kg |
| 6000 | Some air freight and express air services | cm / kg |
| 139 | US domestic ground services | in / lb |
| 166 | US domestic air services | in / lb |
A lower divisor means a higher dimensional weight for the same box, so a service using 5000 will always calculate a heavier "equivalent weight" than one using 6000 for identical dimensions.
Dimensional (volumetric) weight is an estimate of how much space a package takes up relative to its actual weight, calculated as length x width x height divided by a carrier-specific DIM divisor. Couriers bill you for whichever is higher, actual weight or dimensional weight.
Use the smallest box that safely fits your product, avoid excess void fill and packaging, and consider poly mailers or slim boxes for lightweight items. Reducing any one dimension lowers the volumetric weight calculation directly.
It depends on your carrier and service. Most international couriers use 5000 for centimeters and kilograms, some air freight services use 6000, and US domestic carriers typically use 139 or 166 for inches and pounds. Check your carrier's rate documentation to confirm.
Your package was likely billed on dimensional weight rather than actual weight. Bulky, lightweight items like pillows, lampshades or packaging-heavy products often have a dimensional weight well above their actual weight, and carriers always charge the higher of the two.
