Working out your volume and filling a container
Two questions come back with every order: will it fit, and what will the carrier charge on. Enter the dimensions of one carton and the quantity — the calculation runs in your browser.
Updated September 2026
Dimensions of one carton, in centimetres
- Volume of one cartonlength × width × height
- 0.084 m³
- Total volume200 cartons
- 16.8 m³
- Total gross weight
- 2,400 kg
Sea groupage
16.8
revenue tons — the higher of volume in m³ and weight in tonnes. Here it is volume that decides.
Air freight
2,805.6 kg
chargeable weight — actual weight against 2,805.6 kg volumetric. Here it is volume that decides.
Container fill
Loadable volumes allow for dunnage and lost headroom: they are 85% of the theoretical internal volume, which is 33 m³ for a 20 ft, 67 m³ for a 40 ft and 76 m³ for a 40 ft high cube. A loading plan based on the theoretical volume always overflows. Everything is computed on your own machine, and no value leaves the page.
Two pricing rules, not one
The mode of transport changes the rule, and the gap is considerable.
In sea groupage, the chargeable unit is the higher of volume expressed in cubic metres and weight expressed in tonnes. One cubic metre equals one tonne: above a density of 1,000 kg per m³ weight governs; below it, volume does.
In air freight, volumetric weight is calculated with a divisor of 6,000 cm³ per kilo, or about 167 kg per cubic metre. The switch therefore happens six times sooner: goods at 200 kg per cubic metre are already charged on volume by air, while they remain charged on weight by sea.
That is why a low-density product that travels well in a container becomes ruinous by plane.
What a container really takes
Theoretical internal volumes are 33 m³ for a twenty-foot, 67 m³ for a forty-foot and 76 m³ for a forty-foot high cube. Nobody reaches them.
Dunnage, pallets, the height lost under the roof and carton dimensions that rarely divide evenly bring the real load to around 85% of the theoretical volume. That is the basis the calculator works on: a plan drawn up on internal volume overflows systematically at stuffing.
One detail that costs dearly: a two-centimetre difference in carton height can lose a whole tier over the container's height. Dimensions are settled with the factory before production, not after.
The carton is designed, not endured
On a low-density product, packing weighs more in shipping cost than a discount on the unit price. Three trade-offs are made upstream:
- The carton's external dimensions, chosen to sit squarely on a standard pallet rather than to hug the product. A carton three centimetres too wide leaves dead space along the whole length of the pallet.
- The product shipped knocked down, where its design allows. The volume gain often exceeds the cost of assembly.
- The thickness of the dunnage, which protects but occupies. The right level is measured against a breakage history, not the supplier's intuition.
These choices belong in the specification, alongside material and tolerances. If they are not there, the factory will decide alone — according to what it has in stock.
Wooden packaging, a point not to miss
Raw wood packaging — pallets, crates, dunnage — is subject to the international standard ISPM 15: it must be treated against pests and carry a mark attesting that treatment.
A load braced on non-compliant wood can be detained on arrival, and the goods returned or destroyed at the importer's expense. The check is visual and immediate: the mark is there or it is not, and there is no putting it right afterwards.
The remedy is simple, provided you think of it beforehand: require ISPM 15 treated wood in writing, or composite pallets, which fall outside the standard.
Frequently asked questions
- How do I calculate a carton's volume in m³?
By multiplying length, width and height in centimetres, then dividing by one million. A carton of 60 × 40 × 35 cm therefore occupies 0.084 m³. It is the EXTERNAL dimensions that count: what is charged is the space taken in the container, not the contents.
- How many m³ fit in a 20 foot container?
The theoretical internal volume is about 33 m³, but the load actually achievable is around 28 m³ for palletised cartons — roughly 85%. Dunnage, pallets and lost height explain the gap. A forty-foot offers about 67 m³ theoretical, and a forty-foot high cube about 76 m³.
- What is volumetric weight?
A theoretical weight derived from bulk, which transport compares with actual weight and charges on whichever is higher. In sea groupage, one cubic metre counts as one tonne. In air freight the usual divisor is 6,000 cm³ per kilo, or about 167 kg per cubic metre: low-density goods therefore switch to the volume side far sooner by plane.
- Do I pay on weight or on volume?
Neither at your choice: transport charges on whichever of the two is higher, converted into the same unit. The useful question is rather which one governs in your case, because that is the one to act on. If it is volume, packing is the lever; if it is weight, only the quantity shipped is.
- What is the ISPM 15 standard?
An international standard requiring raw wood packaging — pallets, crates, dunnage — to be treated against pests and to carry a mark attesting that treatment. A load braced on non-compliant wood can be detained on arrival and returned at the importer's expense. Composite pallets are not subject to it.
- Does the calculation account for the stowage plan?
No. It compares a total volume with a capacity, which is enough to tell whether you are far from or close to a full load. Actual arrangement depends on carton dimensions, palletisation and stackability: two consignments of the same volume do not load the same way. On a tight file, only a stowage plan drawn up by the freight forwarder settles it.
A load to optimise?
We discuss packing with the factory before production, where the saving is made. Tell us about your product.
Sourcing, quality control, logistics: our services can be commissioned separately or together.