Container Capacity Guide — 20ft vs. 40ft vs. 40HC Compared

"Will this cargo fit in a 20ft, or do I need a 40ft?" is a question exporters run into on nearly every quote. The right answer depends on more than the cargo's CBM — you need internal dimensions, weight limits, and cost efficiency together. This guide compares 20ft Dry (20DC), 40ft Dry (40DC), and 40ft High Cube (40HC) using actual internal container dimensions.

Internal dimensions and volume by container type

Containers should be compared by their internal (loadable) dimensions, not their external size:

• 20ft Dry (20DC): internal 5,898 × 2,352 × 2,393mm → approximately 33.2 m³
• 40ft Dry (40DC): internal 12,032 × 2,352 × 2,393mm → approximately 67.7 m³
• 40ft High Cube (40HC): internal 12,032 × 2,352 × 2,698mm → approximately 76.4 m³

40DC and 40HC share the same length and width — the only difference is 305mm more height on the 40HC, which is why it's preferred for bulky, lightweight cargo like furniture, apparel, and finished consumer goods.

Max payload doesn't scale the way you'd expect

This is the part shippers most often overlook. Volume increases in the order 20ft < 40ft < 40HC, but maximum payload runs almost the opposite direction:

• 20DC: approximately 28,200kg
• 40DC: approximately 26,700kg
• 40HC: approximately 26,500kg

The reason is simple: the maximum gross weight (MGW, largely set by road and rail regulations) doesn't vary much by container size, but 40ft and 40HC containers are structurally heavier (higher tare weight) — which actually reduces the cargo weight you can load. In other words, "40ft is bigger, so it holds more" only applies to volume. For dense cargo like steel or machinery, splitting the shipment across multiple 20ft containers can actually be more weight-efficient than one 40ft.

Which container fits which cargo

• Dense cargo (steel, machinery): weight limits are often reached before the container fills up — multiple 20DCs may be more weight-efficient than a single 40ft.
• Bulky, lightweight cargo (furniture, finished goods, bulky packaging): space fills before weight does, so a 40HC lowers your cost per cubic meter.
• Small LCL shipments: instead of thinking in container units, use the CBM Calculator to work out exact CBM and Revenue Ton (R/T) figures to compare quotes.
• Mixed cargo, or when you're unsure the layout will actually fit: enter your cargo list into the 3D Loading Simulator to see exactly how many units fit under each container preset — and whether the center of gravity stays safe.

Practical checklist

• Calculate your cargo's density (kg/m³) first — above roughly 165 kg/m³, weight tends to become the limiting factor before volume does.
• Remember that 40ft offers more than double the volume of 20ft, but a lower weight limit — factor this into any quote comparison.
• If your cargo is light relative to its volume, consider 40HC over 40DC — it gives you about 13% more volume for the same freight rate structure.
• The most accurate way to confirm exact loading count is a real 3D simulation, not a manual calculation — gap spacing and rotation choices can shift the theoretical count.