Freight Optimisation: Carton Size, Packing and CBM for China Imports

Freight is priced on space as much as weight. For light, bulky products shipped from China, the amount you pay depends far more on the size of the cartons than on what is inside them. Yet carton size is usually decided by the factory, often by habit, before the buyer has even thought about shipping. A few centimetres of empty space in every carton, repeated across a few hundred cartons, can add noticeably to the freight bill.

This article explains how sea and air freight charge for volume, how to design and specify cartons that use space efficiently, where the limits of optimisation lie, and how to work with a Chinese factory to get it done before production starts.

How Volume Turns Into Freight Cost

Every carton has a volume in cubic metres (CBM): length times width times height, measured in metres. How that volume becomes a price depends on the mode.

• LCL sea freight is charged per revenue ton, the greater of the cargo’s volume in CBM or its weight in metric tons. For most consumer goods, volume wins. Our guide to revenue ton pricing explains this in detail.
• FCL sea freight is charged per container, so the question becomes how many units fit in one box. Better cartons can mean fewer containers, or one container instead of an LCL shipment plus overflow.
• Air freight is charged on chargeable weight: the greater of actual weight and volumetric weight. Under the common IATA convention, volumetric weight in kilograms is length times width times height in centimetres divided by 6,000. Express couriers often use a smaller divisor, commonly 5,000, which makes bulky parcels even more expensive. See chargeable weight explained.

In all three cases, empty space inside cartons is paid for as if it were cargo.

Where Wasted Space Hides

• Oversized master cartons chosen from the factory’s standard stock rather than cut to fit the product.
• Retail boxes with generous padding designed for shelf appeal rather than shipping.
• Assembled products shipped fully built when they could travel knocked down (KD) — tables, racks, shelving and some furniture.
• Products that could nest — buckets, chairs, planters and trays shipped one per box instead of stacked inside each other.
• Soft goods packed loose — pillows, cushions and bedding that could be vacuum-compressed.
• Awkward carton dimensions that do not stack neatly on a pallet or across the container width, leaving unused gaps along walls and at the top.

Designing Cartons That Ship Efficiently

Carton optimisation is a balance between four things: space, strength, handling and presentation.

• Fit the product tightly with just enough inner protection to survive the journey. Ask the factory for the product’s packed dimensions and the carton’s internal dimensions, then compare.
• Choose units per carton deliberately. Changing from 12 to 16 units per carton, or arranging items in a different orientation, can reduce the number of cartons and total volume.
• Size cartons to stack well. Ask the factory or forwarder to run a load plan for a pallet footprint or a container, so the chosen dimensions tile the floor with minimal gaps.
• Keep carton weight manageable. At Chattogram depots and Dhaka warehouses, much cargo is still handled by hand. Very heavy cartons slow unloading and increase dropping and injury risk.
• Specify carton strength. Smaller, fuller cartons can often be made stronger. Corrugated board is described by construction (single-wall, double-wall, commonly called 3-ply or 5-ply) and tested for burst strength, edge crush and box compression. Ask which tests the carton supplier can provide.

A Worked Approach with a Factory

Here is a practical sequence to follow on a new order, without relying on any particular numbers:

• At quotation: ask every supplier for carton dimensions, units per carton and gross weight per carton, not just unit price. You need these to compare quotes from different suppliers on a landed basis.
• At sample: have the sample shipped in its intended retail box and ask for a photo of a fully packed master carton with dimensions marked.
• Before production: ask the factory or your forwarder to propose one or two alternative packing configurations and a container or pallet load plan for each.
• Choose and confirm in writing: carton dimensions, board specification, units per carton and shipping marks should appear on the purchase order or packing specification.
• At inspection: the inspector should measure cartons and check them against the agreed specification, because factories sometimes switch carton suppliers mid-order.

Knock-Down, Nesting and Compression: When They Make Sense

Technique	Best for	Watch out for
Knock-down (KD)	Furniture, shelving, racks, frames	Assembly cost and instructions in Bangladesh; missing hardware
Nesting	Buckets, basins, chairs, planters, trays	Scratching between nested items; sticking together in heat
Vacuum compression	Pillows, cushions, quilts, some garments	Some materials do not recover shape well; check with a sample first
Bulk packing, retail packing locally	Items sold in local-language packaging	Labelling and packaging rules still apply when sold in Bangladesh

Each technique saves space but moves some work or risk elsewhere. The right choice depends on how your customers receive the product and what your team in Bangladesh can realistically handle.

Pallets or Floor Loading

Palletised cargo is faster to load and unload with forklifts, and pallets protect the bottom layer from floor moisture. But pallets themselves take space and weight, and wooden pallets must comply with ISPM 15 wood packaging rules. Floor loading cartons directly into a container usually fits more cargo, which is why many FCL shipments of consumer goods from China are floor loaded. The trade-off is slower, manual unloading at the destination depot or warehouse.

For LCL, many consolidators and CFS operators prefer or require palletised or at least well-stacked uniform cartons, because mixed loose cartons are harder to stow and more likely to be damaged. Ask your forwarder what the origin warehouse expects before deciding.

How Carton Choices Affect Customs Clearance

Carton design has a side effect many importers overlook: it changes how easy your shipment is to examine and count. Bangladesh customs cross-checks the number of packages on the bill of lading and import manifest against what is found, and physical examination means officers open selected cartons to verify contents. Uniform cartons with the same units per carton, clearly marked, make counting and verification quick. Mixed cartons holding several different products slow examination and can raise questions if the packing list does not show exactly what is in each one. Our guide to packing list and invoice mismatches explains why that matters.

The Limits of Optimisation

It is possible to over-optimise. Cartons squeezed so tight that the product has no cushioning will save freight and lose more in breakage. Removing the retail box entirely may save space but hurt sales in shops. Very large master cartons use space efficiently on paper but may be too heavy to handle safely. In air freight, extra padding for fragile items may be worth the volumetric weight. And for dense, heavy goods such as metal parts or tiles, weight rather than volume drives the cost, so carton size matters much less.

The goal is the lowest total cost, including freight, damage, handling and sales impact — not the smallest carton.

Common Mistakes and Their Consequences

• Comparing suppliers on unit price only — the cheaper supplier with bulkier packing can be more expensive landed.
• Not fixing carton specs in writing — the factory changes carton size mid-order and your load plan fails at loading.
• Ignoring the courier divisor — express shipments of light, bulky samples come back with a bill based on volumetric weight far above the scale weight. See our guide to reweigh and volumetric disputes.
• Maximising carton size without checking handling — slow unloading and more drop damage at depots.
• Choosing thin board to save cost — crushed bottom layers in the container.

For more on getting cartons into the container efficiently, read our container loading tips and our guide to custom packaging and labels from China.

Every shipment is different, so we do not publish one-size-fits-all numbers here. If you want help with reviewing carton specifications and load plans for your next China order, contact DE International and ask us for a quote built around your actual product, volume and route. You can also browse our sourcing, freight and C&F services, our China sourcing and buying agent service, or products already available in our shop.