What this works out
Enter the packed dimensions of each carton, crate or loaded pallet and you get the volume of one unit and of the whole consignment in cubic metres, the same figure in cubic feet and litres, and the arithmetic written out line by line so you can check it against a quote.
A part-load rarely holds one size. The form takes a line per size, each with its own unit, and the lines are added — never blended into an average, which is a different calculation with a different answer rather than a rough one.
Every measurement is held internally as an exact fraction rather than a decimal approximation, so 40 × 30 × 25 cm × 10 reads as exactly 0.3 m³ instead of the 0.30000000000000004 that ordinary machine arithmetic produces for that sum.
The options panel adds a volumetric-weight comparison on a divisor you choose, a cost line using a rate you have been quoted, and the consignment as a share of a container's internal volume.
Cubic metres and loading metres are not the same number
Two figures turn up on UK and European road quotes and they measure different things. Cubic metres are volume: length by width by height. Loading metres are floor: one LDM is one metre of trailer length across the full width, and on a standard 2.4 m wide trailer that is 2.4 m² of floor space.
The difference shows up the moment cargo is stackable. Two 1200 × 800 mm pallets placed side by side take up 0.8 LDM whether they are loaded to half a metre or to two metres — the floor they occupy has not changed. Their volume, meanwhile, has quadrupled. A carrier quoting on LDM is selling you floor; a carrier quoting per cubic metre is selling you space.
Converting between them needs a height, and the height is the carrier's assumption rather than a fact about your freight. That is why this page calculates volume and stops there: multiply 2.4 m² by whatever loading height your haulier works to and you have their conversion, but the figure belongs to them.
What is worth doing before you ring anyone is getting the volume right, because both quotes start from measurements of the same pallets.
The formula, with a part-load worked through
In metres there is nothing hidden in it: CBM = length × width × height × quantity.
Start with a loaded europallet. A 1200 × 800 mm footprint loaded to one metre including the pallet is 1.20 × 0.80 × 1.00 = 0.96 m³. Four of them are 3.84 m³, which is 135.6 ft³.
Now a mixed part-load. Ten cartons at 40 × 30 × 25 cm come to 0.03 m³ each, so 0.30 m³. Two crates at 120 × 80 × 100 cm are 0.96 m³ each, so 1.92 m³. The consignment is 0.30 + 1.92 = 2.22 m³ over 12 pieces, or 78.3986 ft³.
Blend the two sizes into an average first and you get a notional 80 × 55 × 62.5 cm unit; twelve of those come to 3.3 m³. More than a cubic metre of difference on a small load, and the sort of gap that turns a quote into a revised invoice.
Quantity is a straight multiplier, which gives you a free sanity check: a declared volume that is not a clean multiple of the single-unit volume points at the measuring or the counting, not at the arithmetic.
Measuring so the figure holds at the depot
Freight is charged on the space a unit occupies on the vehicle, so the measurement that counts is the outside of the finished, packed unit — not the goods, and not the carton's internal capacity.
Measure after wrapping. A loaded pallet bulges, and strapping, corner boards and stretch wrap each add a little. Take the widest point, including anything that overhangs the pallet.
Include the pallet in the height. A 1.8 m load on a 145 mm pallet is a 1.945 m unit, and the trailer has to accommodate all of it.
Round up rather than down. A depot measuring on arrival rounds up, and a figure that is generous to yourself by a centimetre gains nothing.
Irregular shapes are charged on the rectangular space they need, so measure the box that would contain the item rather than the item.
Volumetric weight and what actually gets billed
Volumetric weight puts volume into kilograms so it can be compared against real weight. The carrier takes the consignment in cubic centimetres and divides by a figure it publishes: length (cm) × width (cm) × height (cm) × quantity ÷ divisor.
Chargeable weight is then the greater of the actual weight and that volumetric figure. The "whichever is greater" rule is the genuinely standard part; the divisor is not.
Published values: 6000 is IATA's general rule for air cargo, 5000 is DHL Express's standard for its express products, 3000 matches the 1:3 ratio used on rail and 1000 the 1:1 ratio on sea LCL. Road freight has no general rule — ratios differ by country and by carrier, which for a UK reader is the most common case and the one to confirm before quoting.
The spread is wide. The ten-carton example above is 0.3 m³, which is 300,000 cm³: 50 kg at a divisor of 6000, 60 kg at 5000, 300 kg on the sea LCL 1:1 ratio. If those cartons weigh 12 kg each, an airline bills the 120 kg actual weight while the same freight on a groupage sea service is assessed at 300 kg.
Two things to carry into a booking. Carriers change divisors, apply different ones to different services, and some set a minimum chargeable weight per piece. And this page applies one divisor to the whole consignment; a carrier assessing each piece separately and rounding each up arrives slightly higher.
When the volume stops setting the price
Deep-sea freight divides at roughly one container. Below that you buy space in a shared box and the rate comes per cubic metre or per freight ton — whichever is greater of one tonne and one cubic metre. Above it you take a full container at a flat rate, and the question stops being what the volume costs and becomes whether the cargo fits.
Published internal volumes answer the second question only approximately. Hapag-Lloyd's example specifications put a 20ft at 33.2 m³, a 40ft at 67.7 m³ and a 40ft high cube at 76.3 m³, and note themselves that these are examples because containers differ by manufacturer.
They are a ceiling nobody reaches. That volume assumes the box is filled corner to corner with no gaps. Pallets leave dead space along the walls, cartons cannot always be stacked to the roof without crushing, the door aperture is narrower than the container, and the payload limit often bites before the volume does.
So the container line in the result is a share of a geometric volume and says as much. Whether a load actually goes in is a question for a forwarder's load plan.
Common mistakes
Quoting loading metres as though they were cubic metres. Different measurements, different units, and the gap grows with the loading height.
The wrong power of ten. Centimetres become cubic metres by dividing by 1,000,000 and millimetres by 1,000,000,000, because the conversion is cubed along with the dimensions. Dividing centimetres by 100 is out by ten thousand times.
Measuring the goods rather than the packed unit. Packaging, void fill and the pallet all take up space that is charged for.
Averaging sizes on a part-load. Covered above, and worth repeating because nothing about it looks wrong on the page.
Reading a container's capacity as usable space. Internal volume describes an empty box; loading efficiency is a separate question, and palletised freight reaches a good deal less.
What this page does not do
It works out volume and converts units. It holds no freight rates, no carrier tariff and no customs rule, and it cannot tell you what a movement will cost. The cost line multiplies your volume by a rate you type in, leaving out minimum charges, surcharges, a freight-ton basis, local handling and everything else on a real invoice.
Volumetric weight is calculated across the whole consignment on the divisor you select. A carrier may use another, assess each piece separately, or apply a minimum, so read the figure as a check on a quote rather than a prediction of one. Container capacities are geometric volumes from a published specification and say nothing about whether cargo will load.
Each edge is capped at 100 m and each line at 1,000,000 pieces, well past any real consignment and enough to keep the exact arithmetic instant. It all runs in your browser and nothing you type leaves the page.
Sources and methodology
Unit conversions are exact by definition and implemented as exact ratios rather than decimal approximations: 1 inch = 2.54 cm and 1 foot = 0.3048 m exactly (NIST, Guide to the SI, Appendix B), and the litre is exactly one cubic decimetre, so 1 m³ = 1,000 L.
The 6000 divisor and the rule that the greater of actual and volumetric weight is billed come from IATA's material on air cargo tariffs and rules. The 5000 divisor is DHL Express's published standard. The 1:3 rail and 1:1 sea ratios, and the observation that road ratios vary by carrier, come from DHL Global Forwarding's guide to chargeable weight.
Container capacities of 33.2 / 67.7 / 76.3 m³ are Hapag-Lloyd's published example specifications, quoted with that carrier's own caveat that specifications vary by manufacturer.
The loading metre is defined here arithmetically — one metre of trailer length across a 2.4 m width, so 2.4 m² of floor — and no loading height is assumed, because that figure belongs to the carrier quoting you.
Every worked figure on this page is recalculated by tests/cbm-lib.test.js and checked there against a hand calculation.