Container Load Calculator

Why container utilisation determines your landed cost

A full container load (FCL) from Shanghai to Melbourne costs roughly AU$2,800-4,500 depending on season and carrier. A less-than-container load (LCL) shipment of the same route costs AU$60-90 per cubic metre. At those rates, an importer shipping 20 CBM of product pays AU$1,200-1,800 via LCL or books a 20ft container (33 CBM capacity) for AU$2,200-3,200. The container wins on cost per unit only if you fill at least 60-70% of it.

Get the utilisation estimate wrong and the cost difference goes the other direction. A wholesaler who books a 40ft container expecting 800 cartons but can only fit 550 due to pallet dimensions is paying full-container freight for two-thirds of the space. The unused 22 CBM is dead cost that lands directly on the per-unit landed cost.

This calculator estimates both volume and weight utilisation so you can determine the break-even point before committing to a container booking. It supports 20ft standard, 40ft standard, 40ft high cube, and refrigerated containers.

Container types and usable dimensions

Published container dimensions are external measurements. The internal dimensions you can actually load into are smaller, and the door opening is smaller again. Refrigerated containers lose an additional 10-15% of internal volume to insulation and the cooling unit at the rear wall.

*Payload figures reflect typical Australian road-legal limits, not the container's rated maximum gross weight. Actual limits vary by route, state, and whether the carrier holds a Higher Mass Limits (HML) permit. Confirm with your transport provider.

Worked example: wholesale importer, mixed carton shipment

A Perth wholesale distributor imports consumer electronics from Shenzhen. The shipment includes two product types:

• Product A: 400 cartons, each 60 × 40 × 35 cm, 8 kg per carton
• Product B: 200 cartons, each 45 × 30 × 25 cm, 12 kg per carton

Product A occupies 33.6 CBM (400 × 0.084 CBM each) and weighs 3,200 kg. Product B occupies 6.75 CBM (200 × 0.03375 CBM each) and weighs 2,400 kg. Total: 40.35 CBM and 5,600 kg.

A 40ft standard container has 67.5 CBM usable volume. This shipment fills 60% of the volume and uses only 20% of the weight capacity. The shipment is volume-limited. The distributor has two choices: book a 40ft at 60% utilisation, or split across two 20ft containers at near-full utilisation. Two 20ft containers typically cost 15-20% more than one 40ft, so the single 40ft at 60% fill rate is still cheaper unless the second 20ft can be filled with additional stock.

If the total freight cost for the 40ft is AU$3,800, the freight cost per carton is AU$6.33 across 600 units. That figure feeds directly into the landed cost calculation alongside customs duty, import GST, and local cartage.

Common mistakes in container load planning

Ignoring pallet dimensions. A standard Australian pallet is 1,165 × 1,165 mm. Two pallets side by side are 2,330 mm wide, which fits inside a container's 2,350 mm internal width with 20 mm clearance. But if the cartons overhang the pallet edge by even 30 mm, the second pallet row will not fit and you lose an entire tier of loading capacity. Always calculate from palletised dimensions, not loose carton dimensions.

Forgetting tare weight. A 40ft container weighs 3,700-4,200 kg empty. The truck and trailer add another 10,000-15,000 kg. Australian gross vehicle mass limits (typically 42,500 kg on standard roads) mean the actual cargo you can load is whatever remains after subtracting the container, chassis, and truck weight. For dense cargo like tiles, steel fittings, or canned goods, this limit hits well before the container is volumetrically full.

Not accounting for load securing. Lashing bars, dunnage, and airbags take up space and weight. Budget 2-5% of both volume and payload for securing equipment. A tightly packed container with no space for load securing will shift during transit and arrive with damaged product.

Using volume-only estimates for heavy goods. A container of ceramic tiles fills 30% of the volume but 100% of the weight. If you estimate based on how many cartons fit volumetrically, you will overcommit and either pay overweight surcharges or need to short-ship.

How container loading connects to freight AP

Every import shipment generates multiple invoices: the supplier's commercial invoice, the freight forwarder's invoice (covering sea freight, terminal handling, and documentation fees), the customs broker's invoice, and the local cartage invoice from port to warehouse. Each invoice needs different GST treatment, and each line within those invoices may need a different account code.

The freight cost per unit you calculate here feeds into the landed cost, but only if every freight-related invoice is coded correctly in your accounting system. International sea freight is GST-free. Customs clearance charges carry GST. Local cartage carries GST. Processing these invoices under a single GST code produces errors on every shipment. For a detailed breakdown of how to code each component, see the import GST and customs duties coding guide.

For wholesale businesses processing 10-20 import shipments per month, automating the freight invoice coding eliminates the most common source of BAS errors in the AP process. See freight invoice processing for construction and wholesale for how AP automation handles carrier invoices specifically.

How to use this calculator

1. Select your container type from the presets (20ft, 40ft, 40ft high cube, or reefer).
2. Enter item dimensions in centimetres, weight in kilograms, and the quantity for each product type.
3. Add multiple item types if you are loading a mixed shipment with different carton sizes.
4. Enter the total freight cost to calculate the per-unit shipping cost for your landed cost analysis.
5. Review both volume and weight utilisation. If one hits 100% before the other, that is your binding constraint.

Frequently asked questions

What is the difference between FCL and LCL shipping?

FCL (Full Container Load) means you book an entire container for your shipment alone. LCL (Less than Container Load) means your goods share container space with other shippers. FCL is cheaper per cubic metre when you can fill at least 70-80% of the container. Below that threshold, LCL is usually more cost-effective because you only pay for the space you use.

What are the road weight limits for containers in Australia?

Australian road weight limits restrict container payloads below the container's rated maximum. A 40ft container has a maximum gross weight of about 30,480 kg, but after subtracting tare weight (3,700-4,200 kg) and truck weight limits, the road-legal payload is typically 25,000-28,000 kg depending on the route, state regulations, and whether the carrier holds a Higher Mass Limits (HML) permit.

How do I know if my shipment is volume-limited or weight-limited?

Calculate both. If your items fill the container's volume before reaching its weight limit, the shipment is volume-limited (common with furniture, plastics, and packaged consumer goods). If the weight limit is reached before the volume is full, it is weight-limited (common with steel, stone, tiles, and machinery). Knowing which constraint applies determines whether you should optimise for packing density or weight distribution.

What is a high cube container and when should I use one?

A 40ft high cube container is one foot (30.5 cm) taller than a standard 40ft container, giving roughly 76 cubic metres of internal volume compared to 67. Use a high cube when your cargo is volume-limited and the extra height helps: stacking additional pallet layers, fitting taller machinery, or packing bulky items that would waste headroom in a standard container. The freight cost difference is usually AU$100-300.