What this works out
Enter the packed dimensions of each carton, crate or wrapped 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 so you can check it against a quote.
A consignment rarely holds one size. The form takes a line per size, each with its own unit, and adds them — never blends them into an average, which produces a different answer rather than a near 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 gives for that product.
The options panel adds the weight comparison, a cost line using a rate you have been quoted, and the consignment as a share of a container's internal volume.
Cubic conversion: kilograms per cubic metre
Australian road and courier rate cards normally express the volume-to-weight relationship as a cubic conversion — the kilograms a carrier treats one cubic metre as weighing — rather than as the divisor used on international air freight. Multiply your cubic metres by the conversion and you have the cubic weight in kilograms. The carrier then bills on the greater of that and the actual weight, which is the same "whichever is greater" rule used everywhere else.
This calculator's divisor field wants the other form, and converting between them is one division: divisor = 1,000,000 ÷ (kilograms per cubic metre). A conversion of 250 kg per m³ is a divisor of 4,000. 200 kg per m³ is 5,000. 166.67 kg per m³ is exactly 6,000 — the international air figure, which is why it and an Australian road conversion can look like different systems when they are the same arithmetic.
It works because a cubic metre is exactly 1,000,000 cubic centimetres. The divisor form divides centimetres by a number; the conversion form multiplies metres by a number; and 1,000,000 is the bridge.
Which conversion applies is your carrier's decision and nothing here guesses at it. Read it off the rate card, put the divisor in the options panel, and the weight comparison below the result does the rest. The spread matters: the same 1.6287 m³ pallet is 407.17 kg at 250 kg per m³ and 325.73 kg at 200, which is a fifth less billed weight for freight that has not changed at all.
The formula, with a pallet consignment worked through
In metres the formula holds nothing back: CBM = length × width × height × quantity.
Take the 1165 × 1165 mm Australian standard pallet footprint, loaded to 1.2 m overall including the pallet. That is 1.165 × 1.165 × 1.20 = 1.6287 m³ per pallet, so four of them come to 6.5147 m³.
Load the same footprint to 1.8 m instead and each pallet is 2.4430 m³. The floor space has not changed and the pallet count has not changed; only the height has, and the volume went up by half.
A mixed consignment adds line by line. Ten cartons at 40 × 30 × 25 cm are 0.03 m³ each, so 0.30 m³; two crates at 120 × 80 × 100 cm are 0.96 m³ each, so 1.92 m³. Together that is 2.22 m³ over 12 pieces, or 78.3986 ft³. Averaging the two sizes first gives a notional 80 × 55 × 62.5 cm unit, and twelve of those come to 3.3 m³ — more than a cubic metre of difference.
Quantity is a straight multiplier, which gives you a free check: a declared volume that is not a clean multiple of the single-unit volume points at the measuring or the counting rather than the sum.
Measuring so the figure holds at the depot
Freight is charged on the space a unit occupies on the vehicle, so what counts is the outside of the finished, wrapped unit — not the goods, and not the carton's internal capacity.
Measure after wrapping. A loaded pallet bulges, and strapping, corner boards and stretch film each add a little. Take the widest point, including anything overhanging the pallet.
Include the pallet in the height. A 1.05 m load on a 150 mm pallet is a 1.2 m unit, and that is what the vehicle has to take.
Round up rather than down. A depot re-measuring on arrival rounds up, and a centimetre of optimism gains nothing.
Irregular items are charged on the rectangular space they need, so measure the box that would contain the item rather than the item.
Divisors on the international legs
Once freight leaves the country the divisor form takes over: volumetric weight (kg) = length (cm) × width (cm) × height (cm) × quantity ÷ divisor, with chargeable weight the greater of that and the actual weight.
Published values: 6000 is IATA's general rule for air cargo, 5000 is DHL Express's standard for its express products, 3000 corresponds to the 1:3 ratio used on rail and 1000 to the 1:1 ratio on sea LCL. Road freight has no general rule, which is exactly why Australian domestic carriers publish their own cubic conversions.
A smaller divisor makes the same box heavier on paper. Ten cartons at 40 × 30 × 25 cm are 0.3 m³, or 300,000 cm³: 50 kg at a divisor of 6000, 60 kg at 5000, and 300 kg on the sea LCL ratio. If the cartons weigh 12 kg each, an airline bills the 120 kg actual weight while the same freight moving LCL is assessed at 300 kg.
Carriers change divisors, apply different ones to different services, and some set a minimum chargeable weight per piece. This page applies the divisor you choose across the whole consignment; a carrier assessing each piece and rounding each up lands a little higher.
Against a container
Sea freight divides at roughly one container. Below it 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 book a container outright, and the question becomes whether the cargo fits rather than what the volume costs.
Published internal volumes are where that starts. Hapag-Lloyd's example specifications give 33.2 m³ for a 20ft, 67.7 m³ for a 40ft and 76.3 m³ for a 40ft high cube, with the carrier's own note that these are examples because containers differ by manufacturer.
They are a ceiling nobody reaches. The figure assumes corner-to-corner packing 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 box, and the payload limit often bites first — and the 1165 mm square footprint tiles a container differently from a 1200 × 800 europallet, which is worth checking with a forwarder rather than assuming.
So the container line in the result is a share of a geometric volume and says so.
Common mistakes
Treating a cubic conversion as a divisor, or the other way round. One multiplies cubic metres, the other divides cubic centimetres. Putting 250 into the divisor field instead of 4,000 overstates the weight by a factor of sixteen.
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.
Measuring the goods rather than the wrapped unit. Packaging, void fill and the pallet all take space that is charged for.
Averaging sizes on a mixed consignment. Covered above, and easy to miss because nothing about the result looks wrong.
Reading a container's capacity as usable space. Internal volume describes an empty box; loading efficiency is a separate question and palletised freight reaches well under it.
What this page does not do
It works out volume and converts units. It holds no freight rates, no carrier tariff, no cubic conversion 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, fuel levies, a freight-ton basis, local handling and everything else on a real invoice.
Cubic and volumetric weight are calculated across the whole consignment on the figure you supply. A carrier may use a different one, assess each piece separately, or apply a minimum, so read the result 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, far beyond any real consignment and enough to keep the exact arithmetic instant. Everything 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 relationship between a cubic conversion and a divisor is stated here as arithmetic and nothing else: a cubic metre is exactly 1,000,000 cubic centimetres, so divisor = 1,000,000 ÷ (kilograms per cubic metre). No carrier's cubic conversion is named or implied, because the figure belongs to a rate card, varies between carriers and services, and is revised.
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 note 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.
Every worked figure on this page is recalculated by tests/cbm-lib.test.js and checked there against a hand calculation.