A mixed container is how most importers in Lagos, Accra, Mombasa and Dar es Salaam actually buy: twenty small lines from Yiwu instead of one full container of one product. It is also where most of the expensive mistakes happen, because every extra line is another carton label, another quantity and another document to get wrong.
The four things that go wrong
- Quantity drift — the carton count at loading does not match the invoice. It is usually discovered after the container is sealed.
- Crushed cartons — light goods packed under heavy ones, or cartons loaded without a floor sheet.
- Label errors — one factory's cartons carry the wrong line name, and the whole container waits while it is sorted.
- Missing documents — the vessel arrives before SONCAP, the certificate of origin or the packing list does.
Do the CBM maths before you book
Every supplier quotes in cartons. Your forwarder quotes in cubic metres. Convert early, or you will be negotiating space on the quay.
| Container | Internal volume | Realistically usable | Typical payload |
|---|---|---|---|
| 20GP | about 33 CBM | 26-28 CBM | up to 28,000 kg |
| 40GP | about 67 CBM | 55-58 CBM | up to 26,000 kg |
| 40HQ | about 76 CBM | 64-68 CBM | up to 26,000 kg |
Usable volume is lower than internal volume because pallets, dunnage, door space and irregular carton shapes waste room. On dense goods — tiles, tools, batteries — weight runs out long before volume does. Always check both numbers.
If the order is under roughly 12 to 15 CBM, the maths usually favours LCL rather than a part-loaded container. Above that point the per-cubic-metre cost of a 20GP starts to win, even though you are paying for space you do not fill. Ask your forwarder for both quotes on the same day, because the crossover moves with the freight rate and the sailing schedule.
Weight is the trap on a mixed load. A container full of light plastics looks impressive and weighs nothing; a container of batteries, tiles or hand tools hits the road weight limit at half the volume. Tell your forwarder the gross weight per line, not just the total, so they can flag an overweight booking before it reaches the terminal.
A container that is "full" at 55 CBM of cartons is normal. A container "full" at 75 CBM of irregular cartons means someone is planning to force the doors shut.
What every carton label needs
The label is the cheapest insurance in the whole shipment. On a mixed load it should carry:
- Line reference that matches your packing list exactly — not the supplier's internal code alone.
- Pieces per carton and total cartons in the line.
- Gross weight and carton dimensions.
- Your company name and the destination port.
- Carton number out of total (for example 17 of 240) so a missing box is obvious.
Loading order
Load heavy goods at the front and along the floor, light goods on top and toward the doors. Anything that can leak or smell goes away from textiles and food-contact goods. If you are loading for several destinations in one container, the first port to discharge goes nearest the doors.
Photograph the container at three points: empty, half loaded, and sealed with the seal number visible. Those three photos settle most arguments about damage.
Documents your forwarder will ask for
- Commercial invoice — per line, with HS codes.
- Packing list — carton count, dimensions, gross and net weight.
- Bill of lading — issued after the container is loaded.
- Certificate of origin — needed for preferential duty in several markets.
- SONCAP for Nigeria, PVoC for Kenya and Tanzania — arranged per regulated product, not per container.
Compliance is the item that most often delays a mixed container, because one regulated line can hold the whole shipment. Confirm which of your lines need a certificate before you pay a deposit, not after the goods are at the port.
What to ask before you commit
- How many cartons and how many CBM is my order at the moment, line by line?
- Can you send photos of the cartons labelled and staged before loading?
- Which lines need SONCAP or PVoC, and who pays the testing?
- What is the seal number and can I see the sealed container photo?
- Who is my single contact if something is short on arrival?
A supplier who can answer all five without checking with someone else is usually the one who actually holds the stock. That is the difference between buying from a warehouse and buying from a WeChat profile.