Container Loadability Calculator: Cartons per Container by CBM and Weight
Quoting ocean freight starts with one question: how many cartons fit in a container. This calculator checks both limits, volume and weight, and tells you the number per container and how many containers the order needs.
Your numbers
Outer dimensions of the shipping carton, not the product.
Product plus packaging.
Practical usable volume is below the internal cubic capacity because of door gaps, dunnage and stacking loss.
Check the carrier and road limits for the lane. Many lanes cap below the container rating.
Share of usable volume you can actually fill with your carton size.
Your results
Planning estimate. Real loading depends on carton orientation, pallets, dunnage, carrier weight limits and stowage rules. Confirm with your forwarder.
Cartons per container vs carton height
Sweeps Carton height from 10 to 80, holding your other inputs fixed.
Automate container fill from your ERP item master
Optional: a short review of how to pull carton dimensions and weights from your ERP into automatic container planning.
Optional. The tool and every export work without this. No spam.
How to use the container loadability calculator
Enter the outer carton dimensions in centimetres, the gross weight per carton and the order quantity. Pick the container type, set the maximum cargo weight for your lane, and adjust packing efficiency for how well your carton size tessellates. The calculator converts to cubic metres, finds how many cartons the volume allows, how many the weight allows, and takes the lower number. Dense goods such as castings, bearings and tooling hit the weight limit first; light goods such as foam, plastics and electronics enclosures hit the volume limit first.
The method behind the numbers
Carton CBM equals length times width times height in centimetres divided by one million. Cartons by volume equal usable container CBM times packing efficiency, divided by carton CBM, rounded down. Cartons by weight equal the permitted payload divided by carton weight, rounded down. The binding constraint is the smaller of the two. Containers needed is the order quantity divided by that figure, rounded up, so a nearly empty last container is visible in the result.
- A 20ft container is often weight limited, a 40ft high cube is usually volume limited.
- Palletised cargo loses volume to pallet height and 1 to 2 centimetres of gaps per side.
- Road weight limits at the destination can be lower than the container rating.
Reading the result and the chart
If volume utilization is high and weight utilization is low, the cargo is light and a high cube container may be the better buy. If weight utilization is near 100 percent while volume is low, you are paying for air; consider a 20ft container or sharing the load. The chart shows how cartons per container fall as carton height grows, which helps when you can still change the pack design. A small change in carton dimensions can add or remove a whole carton layer.
Common mistakes
The most common error is using product dimensions instead of outer carton dimensions. The second is using the container's internal cubic capacity as if all of it were loadable. Others include ignoring that a container payload is not the same as its tare plus cargo gross, forgetting pallet weight, and forgetting that mixed carton sizes need a separate calculation per size. When one order has several SKUs, run each size and add the CBM.
Frequently Asked Questions
What is the usable CBM of a 40ft container?
A 40ft standard container has roughly 67 CBM of internal volume, but practical usable volume is closer to 55 to 60 CBM once you allow for stacking loss, door gaps and dunnage. A 40ft high cube is about 76 CBM internal and 65 to 70 CBM usable.
Why does my container weigh out before it cubes out?
Dense cargo such as metal parts, castings and fasteners reaches the payload limit while leaving empty space. The calculator shows weight utilization so you can see this and choose a smaller container or split the load.
Should I use gross or net weight?
Use gross weight per carton, including packaging, pallets and dunnage. Carriers and road authorities limit total cargo weight, not net product weight, and the verified gross mass is also required for container declarations.
Does this work for pallets?
Yes. Enter the pallet's outer length, width and height as the carton and the loaded pallet weight. Set packing efficiency lower, around 80 to 85 percent, to reflect floor gaps and the pallet footprint.
If your ERP already holds item dimensions and weights, Netray can calculate container fill for every open purchase order automatically, so buyers see the freight impact before they release the order.
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