What is volumetric (dimensional) weight?
Carriers do not just charge for how heavy a shipment is — they also charge for the space it takes up. A box of pillows weighs almost nothing but fills a lot of a plane or truck, so carriers convert its volume into a weight, called volumetric weight (also “dimensional” or “DIM” weight). You are billed on whichever is greater: the actual weight on the scale, or the volumetric weight. That billed figure is the chargeable weight.
The formula is the same everywhere — only the divisor changes:
volumetric weight = (length × width × height) ÷ divisor
The divisors, by shipping mode
A smaller divisor produces a larger volumetric weight, so the same box costs more to ship by express courier (5000) than by air freight (6000). Sea LCL works differently — it has no divisor at all.
| Mode | Metric (cm³/kg) | Imperial (in³/lb) | What it means |
|---|---|---|---|
| Air freight (IATA) | 6000 | 166 | 1 m³ ≈ 167 kg |
| Express courier (FedEx / UPS / DHL) | 5000 | 139 | 1 m³ = 200 kg |
| Sea LCL (W/M revenue ton) | no divisor — tonne vs m³ directly | 1 m³ compared with 1,000 kg | |
These are the common standards. UPS US-domestic retail uses 166 in³/lb (6000), and DHL applies 4000 in the UAE — which is why the calculator lets you override the divisor for air and express.
Metric vs imperial
Keep your units consistent with the divisor. Centimetres with 5000 or 6000 give a result in kilograms; inches with 139 or 166 give a result in pounds. Mixing them (e.g. inches with 5000) produces a meaningless number. The calculator switches the divisor automatically when you toggle cm / kg and in / lb.
Sea LCL: the W/M revenue ton
Less-than-container-load (LCL) ocean freight does not use a volumetric divisor. Instead it is billed per revenue ton (RT), also written W/M for “weight or measurement”: the carrier takes the greater of your weight in metric tonnes (kilograms ÷ 1000) and your volume in cubic metres (CBM). A dense 8-tonne, 3 m³ pallet is billed as 8 RT; a light 2.5-tonne, 4 m³ pallet is billed as 4 RT.
Why bulky-but-light shipments cost more
When a box's volumetric weight is higher than its actual weight, you are effectively paying to ship air. A 100 × 80 × 60 cm carton that weighs only 25 kg has a volumetric weight of 80 kg by air (480,000 cm³ ÷ 6000), so you pay for 80 kg and 55 kg of that is empty space. The fix is to ship denser: smaller boxes, less void fill, the right pack size.
Packaging tips to cut volumetric weight
- Right-size the box — every extra centimetre of void counts against you at the divisor.
- Replace bulky void fill with thinner protection where the product allows.
- Flat-pack or nest items so the outer carton is as small as the contents permit.
- Round measurements the way your carrier does (usually up to the next whole cm or inch) before you compare quotes.
- For multiple boxes, compare consolidating into fewer, denser cartons against shipping them loose.
Frequently asked questions
Is volumetric weight the same as dimensional weight?
Yes. “Volumetric weight”, “dimensional weight” and “DIM weight” all mean the same thing — a weight derived from a shipment's volume so carriers can charge for the space it uses.
Which weight am I actually charged on?
For air freight and express courier you are charged on the chargeable weight: the greater of the actual (gross) weight and the volumetric weight. For sea LCL it is the greater of the weight in tonnes and the volume in m³.
Why do FedEx, UPS and DHL use 5000 but air freight uses 6000?
They are simply different industry conventions. Express couriers settled on 5000 cm³/kg (139 in³/lb) for most international services, while the IATA air-cargo standard is 6000 cm³/kg (166 in³/lb). The smaller 5000 divisor means express bills a higher volumetric weight for the same box.
Can I trust the exact figure?
Treat it as an estimate. Carriers round (often up to the next 0.5 kg), apply a minimum chargeable weight, and can use a different divisor by service, account type or lane. Always confirm the divisor with your carrier — the calculator lets you override it.
Sources
Divisors verified on against the carriers' own published pages: