Container Load Calculator (CBM Calculator)

Dividing your total CBM by a container’s stated capacity will tell you the wrong answer almost every time. A 40ft high cube is quoted at 76 CBM, but rectangular cartons cannot tile perfectly inside a rectangular steel box, and whatever is left at the end of a row or the top of a stack is dead space. Real loads land between 80 and 85 percent of nominal, and if you plan on the nominal figure you will be one container short.

Container Load Calculator works the way a stuffing plan actually works. Enter your cartons and it computes total CBM and gross weight, then tests every orientation of every carton against the internal dimensions of each container type to find how many genuinely fit — per layer, how many layers high, and how many in total. It respects your maximum stack height, so fragile cargo that can only go three high is not silently planned to the roof.

Critically, it checks both limits at once. Space and payload are independent ceilings, and dense cargo hits the 28 tonne payload of a 20ft with the box half empty while textiles fill the volume at a third of the weight allowance. The calculator names which limit binds for your cargo, shows the number of containers needed for every type side by side, and flags the cases where two 20ft units beat one 40ft — a result that surprises most shippers and is purely a function of density.

• True carton fit, not CBM division: Every carton orientation is tested against each container’s internal dimensions to give a real fit count rather than a theoretical volume ratio.
• Six container types: 20ft standard, 40ft standard, 40ft high cube, 45ft high cube, 20ft reefer and 40ft high cube reefer, with nominal internal dimensions and plated payloads.
• Both limits checked: Volume and payload evaluated independently, with a clear statement of which one binds and how much of the other is left unused.
• Layer and orientation output: Cartons per layer, layers high, best orientation and remaining floor space — the detail a stuffing plan needs.
• Stack height limit: Cap the number of layers to respect carton compression strength or fragile cargo, and see the capacity cost of that constraint.
• Containers needed per type: Side-by-side count for every container type with utilisation percentages, so the booking decision is visible at a glance.
• Two 20ft versus one 40ft check: Automatically flags dense cargo where the payload ceiling makes two smaller boxes carry more than one larger one.
• Practical loading factor: Adjustable 75 to 95 percent efficiency allowance for dunnage, pallets and working space, applied transparently rather than hidden.
• Multi-line cargo: Any number of carton types, each with its own dimensions, weight, quantity and stackability.
• Metric and imperial: Enter in cm/kg or in/lb with correct conversion throughout.
• Fully client-side: No account, no upload, nothing stored.

1. Enter your cartons. Length, width, height, gross weight per carton and quantity for each type. Use packed outer dimensions, including any pallet if you are shipping palletised.
2. Set the maximum stack layers. If compression strength or fragility limits how high cartons can go, enter it here. Leaving it unlimited assumes you can stack to the roof.
3. Choose a loading efficiency. 85 percent is a sound default for mixed carton loads; drop to 75 to 80 percent for irregular cargo or heavy pallet use.
4. Read the fit table. Check cartons per container, layers high and the best orientation for each container type, not just the CBM figure.
5. Identify the binding limit. If payload binds, more space will not help you — split the consignment or reduce density per container. If volume binds, look at carton sizing and orientation.
6. Compare container options. Look at containers needed and utilisation across types, and check the two-20ft flag if your cargo is dense.
7. Confirm before booking. Ask your carrier for the actual internal dimensions and plated payload of the container assigned, since both vary between units.

Example 1 — Light bulky cargo, volume binds. 500 cartons at 60 x 40 x 40 cm weighing 9 kg each: 48 CBM and 4.5 tonnes. Volume needs a 40ft high cube; weight uses only 17 percent of its payload. The entire decision is about space, so orientation and carton sizing are where the savings are, and the high cube is clearly better value than the 40ft standard.

Example 2 — Dense cargo, payload binds. 900 cartons of ceramic tiles at 40 x 30 x 20 cm weighing 32 kg each: 21.6 CBM and 28.8 tonnes. The volume would fit comfortably in a 40ft standard at under a third full, but 28.8 tonnes exceeds the payload of any single container. You need two units, and each will look almost empty — that is normal and correct for dense freight.

Example 3 — Where two 20ft beat one 40ft. The same tile shipment in two 20ft containers gives roughly 56 tonnes of combined payload against about 26.7 tonnes in a single 40ft. For dense cargo the smaller boxes carry more than double the weight, and even at a higher combined freight cost the cost per tonne is frequently lower. The calculator flags this automatically.

Example 4 — Orientation and the stack limit. A carton of 58 x 38 x 42 cm fits 4 across the 235 cm width with 3 cm wasted; rotated, it fits 6 across with 7 cm wasted but adds a full row per layer. Cap stacking at 4 layers because of compression strength and the achievable load drops by roughly a fifth against stacking to the roof — a constraint worth knowing before you promise a shipping date.

• Book the right container first time: Planning on real carton fit rather than nominal CBM prevents the discovery that your cargo does not fit on loading day.
• Know which limit binds: Volume and payload are separate ceilings, and the fix for each is completely different.
• Capture orientation gains: Rotating a carton can add a full row per layer, which is free capacity your stuffing plan can specify.
• Avoid the 40ft assumption: For dense cargo two 20ft containers often carry more weight and cost less per tonne, and almost nobody checks.
• Plan around fragile cargo honestly: A stack limit is a real constraint, and seeing its capacity cost lets you price it or redesign the carton.
• Choose standard versus high cube on evidence: The extra height only pays if your carton height uses it, and the layers figure shows whether it does.
• Free and private: No sign-up, nothing uploaded, instant results.