Volumetric weight calculator
Work out the volumetric and chargeable weight of any shipment the way South African couriers bill it — per piece, at the divisor on your rate card.
Chargeable weight
Chargeable weight takes the greater of actual vs volumetric per piece, then sums — the same way courier billing systems rate multi-piece waybills.
How volumetric weight works
A courier vehicle runs out of space long before it runs out of payload. Volumetric weight is how the industry prices that reality: a parcel’s dimensions are converted into a weight equivalent, and the shipment is billed on whichever is greater — the scale weight or the volumetric weight.
The formula
Volumetric weight (kg) = Length × Width × Height (cm) ÷ Divisor
Worked example: a 60 × 40 × 40 cm carton weighing 5 kg on the scale. Its volume is 96,000 cm³; at the standard South African courier divisor of 5,000 that is a volumetric weight of 19.2 kg. Since 19.2 kg > 5 kg, the chargeable weight is 19.2 kg — the parcel is billed at almost four times its scale weight, because that is the vehicle space it occupies.
Which divisor applies to you
The divisor expresses the density at which a parcel switches from being billed by size to being billed by weight. A lower divisor is stricter on bulky cargo.
| Divisor | Break-even density | Typically used for |
|---|---|---|
| ÷ 5,000 | 200 kg/m³ | Standard for SA domestic courier and express services |
| ÷ 4,000 | 250 kg/m³ | Some road-freight and linehaul carriers |
| ÷ 3,000 | 333 kg/m³ | Economy road freight (favours dense cargo) |
| ÷ 6,000 | 167 kg/m³ | International air cargo (IATA convention) |
Divisors vary by carrier and service level — always confirm the one on your rate card. In ParcelOps the divisor is configurable per customer and per service level, so quotes and invoices always use the contracted figure.
Volumetric weight FAQs
What is volumetric weight?
Volumetric weight (also called dimensional weight) converts a parcel's size into a weight equivalent: length × width × height in centimetres, divided by a volumetric divisor. Couriers bill on whichever is greater — actual weight or volumetric weight — so a large, light box is charged for the space it occupies, not what it weighs on a scale.
What volumetric divisor do South African couriers use?
Most South African courier and express services use a divisor of 5,000 (equivalent to 200 kg per cubic metre). Some road-freight carriers use 4,000, and economy road freight is often rated at 3,000. International air cargo commonly uses 6,000. Your courier's rate card or service agreement states which divisor applies.
Why was I charged more than my parcel's scale weight?
Because the parcel's volumetric weight exceeded its actual weight. A box of 60 × 40 × 40 cm weighing 5 kg has a volumetric weight of 19.2 kg at the standard ÷5,000 divisor, so it is billed as 19.2 kg. Vehicle space is the courier's real constraint — bulky parcels consume it faster than heavy ones.
How is chargeable weight calculated on a multi-piece shipment?
Per piece, not on totals. For each piece the courier takes the greater of its actual and volumetric weight, then sums those values across the shipment. A dense piece cannot subsidise a bulky one — which is why packing one consignment into fewer, fuller boxes usually costs less than many half-empty ones.
How can I reduce volumetric weight charges?
Use the smallest box that protects the contents, avoid excessive void fill, and consolidate multiple pieces where possible. Even a few centimetres matter: reducing a 60 × 40 × 40 cm box to 50 × 35 × 35 cm cuts its volumetric weight from 19.2 kg to 12.25 kg at the standard divisor — a 36% saving.
Stop calculating this by hand
ParcelOps rates every waybill automatically — volumetric weight, sliding-scale tariffs, fuel surcharge and VAT — the moment it’s captured.