Volumetric weight explained: why a light parcel can cost more to ship
By the TrueSellerPrice.com team · Published
Carriers charge for whichever is larger: what your parcel weighs on a scale, or what its size “weighs” by their formula. That second number is the volumetric (or dimensional) weight, and for light, bulky products it is usually the one you pay for.
The formula
Volumetric weight (kg) = length × width × height (cm) ÷ divisor
The divisor is set by the carrier and written in its terms. Common values are 5000 for international express services and 6000 for some couriers. In Türkiye the same figure is called desi and is usually worked out with a divisor of 3000. A smaller divisor makes the same box “heavier”, so always use the number from your own carrier agreement.
The carrier then bills the chargeable weight: the larger of the actual weight and the volumetric weight.
Worked example
A box of 40 × 30 × 20 cm holds a 2 kg product.
| Divisor | Volumetric weight | Actual weight | Chargeable weight |
|---|---|---|---|
| 3000 | 8.0 kg | 2 kg | 8.0 kg |
| 5000 | 4.8 kg | 2 kg | 4.8 kg |
| 6000 | 4.0 kg | 2 kg | 4.0 kg |
With every divisor, the box costs more than its contents weigh. The volume is 40 × 30 × 20 = 24,000 cm³, or 0.024 m³.
A smaller box is a price cut
If the same product fits in a 35 × 25 × 15 cm box, the volume falls to 13,125 cm³. With a divisor of 5000 the volumetric weight drops from 4.8 kg to about 2.6 kg — and since the product weighs 2 kg, the chargeable weight falls by almost half. Nothing about the product changed; only the air in the box did.
That is why packaging belongs in pricing. If shipping is one of your larger costs, test two or three box sizes before you set the price.
Whole shipments: CBM
Freight forwarders quote sea and air shipments by volume in cubic metres (CBM). One carton of 40 × 30 × 20 cm is 0.024 m³, so 100 cartons take 2.4 m³. The volumetric weight calculator works this out for you when you enter the number of parcels.
Where it fits in your price
Once you know the chargeable weight, look up the rate on your carrier’s price list and enter it as Shipping you pay in the profit calculator. The break-even price there tells you the lowest price that still covers it.