Guide ยท Loading and special shipments
Container load plan from a packing list: 20 ft and 40 ft capacity
A first container plan needs two totals from the packing list: CBM and gross weight. Compare each with the container's usable volume and payload. Whichever fills first sets the limit, and the ratio of kilograms to CBM tells you which one it will be.
Volume or weight: which one limits the load
A load plan decides how many containers a shipment needs and how the cartons sit in them. The packing list supplies the inputs: total CBM, total gross weight, carton sizes and counts. Divide gross kilograms by CBM to get density. Light, bulky cargo fills the container's volume before its weight limit (it "cubes out"); dense cargo reaches the payload first (it "weighs out").
Each container has a break-even density, its payload divided by its usable volume. A shipment of 52.3 CBM and 6,150 kg is about 118 kg per CBM, below every break-even in the table, so volume sets the limit. On paper it does not fit a 20 ft container (about 33 CBM) but does fit a 40 ft (about 67 CBM), before allowing for gaps between cartons.
General information, not customs or legal advice, and not a stowage plan. Container dimensions and payloads vary by container and shipping line, and road weight limits can be lower than the container's rating. Ask your carrier for the figures that apply to your booking.
Plan a container in six steps
Take the totals
Total CBM and total gross weight from the list. If the rows do not add up to the declared totals, resolve that first.
Work out density
Gross kilograms divided by CBM. For 6,150 kg and 52.3 CBM that is about 118 kg per CBM.
Compare with the break-even
Below the container's break-even density the volume fills first; above it the weight does. Use gross weight, not net; see gross weight vs net weight.
Allow for loading losses
Carton shapes, pallets and gaps mean cartons rarely use all the internal volume. Leave a margin and ask your forwarder or warehouse how much.
Check how the cartons divide
A 60 cm carton fits three across a 2.35 m width and leaves 55 cm unused. The carton sizes and the pallet size decide the real count; see CBM calculation for cartons for the volume side.
Choose the container and confirm
Pick the size and number of containers by the tighter limit, then let the forwarder confirm the actual container and loading method.
Approximate container figures
Typical dry containers. Internal sizes and payloads differ a little by line and container.
| Container, inside L x W x H in metres | Volume (CBM) | Typical payload (kg) | Break-even (kg per CBM) |
|---|---|---|---|
| 20 ft general purpose, 5.9 x 2.35 x 2.39 | about 33 | about 28,000 | about 850 |
| 40 ft general purpose, 12.0 x 2.35 x 2.39 | about 67 | about 26,500 | about 400 |
| 40 ft high cube, 12.0 x 2.35 x 2.69 | about 76 | about 26,300 | about 350 |
Break-even is payload divided by volume. A load below it is volume-limited; above it, weight-limited.
Pallets change the arithmetic
Palletised cargo adds the pallet's own height and weight, and pallet footprints rarely divide the container's 2.35 m width exactly, so the same cartons need more space than their CBM suggests. Ask whether the load will be floor-loaded or palletised before you rely on a CBM-only estimate, and add the pallets to the gross weight.
What goes wrong
- Using net weight. The payload limit applies to the whole cargo with its packing and pallets, which is the gross weight.
- Ignoring density. A load planned on volume alone can exceed the payload, especially with dense goods in a 40 ft.
- Treating list CBM as loadable volume. Pallets, dunnage and gaps take space, so the same cartons need more room than their CBM.
- A wrong CBM on the list. A decimal slip or inches read as centimetres makes the whole plan unreliable.
- Planning each supplier alone. Each supplier's goods seem to fit, but together they need another container; see consolidated packing list for multiple suppliers.
How CargoSheet helps
CargoSheet gives you the starting numbers: total cartons, total CBM and total gross weight, with CBM computed from carton sizes where the list omits it and every total compared with the list's declared figures. It does not plan containers, stack cartons or choose a container size. Try the packing list to Excel converter. Free: 1 file per day, up to 10 pages, no account. Files over 10 pages are converted up to page 10 on the free allowance; a page code converts the whole file, up to 150 pages. See pricing.
Questions
- How many CBM fit in a 20 ft container?
- About 33 CBM of internal volume, though practical loads are usually lower because cartons and pallets leave gaps. A 20 ft container's payload is roughly 28,000 kg, but your carrier's figure applies.
- How many CBM fit in a 40 ft container?
- About 67 CBM in a standard 40 ft and about 76 CBM in a 40 ft high cube, again before allowing for gaps and pallets.
- What is the difference between cubing out and weighing out?
- Cubing out means the cargo fills the container's volume before reaching its weight limit. Weighing out means it reaches the weight limit first. Density, gross kilograms per CBM, tells you which applies.
- Can I plan a container from the packing list alone?
- For a first estimate, yes. A real plan also needs carton and pallet sizes, stacking limits, fragile or dangerous goods rules and the actual container, which the forwarder or the warehouse works out.
- Is the weight limit in the container or on the road?
- Both can apply. The container has a rated payload, and the road legs at origin and destination may have lower legal limits. Your forwarder knows the limits on your route.
- What if the load is less than a container?
- Then it may ship as LCL, usually charged per CBM or per tonne, whichever is greater under the carrier's terms. Ask your forwarder at what volume a part-full container costs less than LCL.
Check a packing list against its own totals
Free: 1 file per day, up to 10 pages, no account.