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Container size calculator: 20ft or 40ft?
Enter your cargo rows or just the total volume and weight. The calculator picks the smallest container, or combination, that takes it with room to load.
Your cargo
Results
Recommendation
40ft container
Volume
70 %
Payload
34 %
- The volume is the limit: the smaller option does not have enough usable space.
- 20ft containerToo much
Volume 142 % · Payload 32 % (28,200 kg)
Usable volume: 85 % of 33.1 m³ = 28.1 m³
- 40ft containerFits
Volume 70 % · Payload 34 % (26,680 kg)
Usable volume: 85 % of 67.6 m³ = 57.4 m³
- 40ft High CubeFits
Volume 62 % · Payload 34 % (26,460 kg)
Usable volume: 85 % of 76.0 m³ = 64.6 m³
Your cargo is copied into the planner, which arranges every piece in 3D.
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How it is calculated
Choosing between a 20ft and a 40ft container comes down to two limits: usable volume and payload. Light cargo runs out of space first, heavy cargo out of weight.
Formula
- usable volume = inside volume × 0.85
- volume fill = cargo m³ ÷ usable volume
- payload fill = cargo kg ÷ payload
- pick the smallest container with both fills at or under 100 %
- Inside volume and payload used: 20ft 33.1 m³ / 28,200 kg, 40ft 67.6 m³ / 26,680 kg, 40ft HC 76.0 m³ / 26,460 kg. Your line’s tare and payload may differ.
- For several containers the cargo is assumed to split freely; fewest containers win, then fewest TEU.
Worked example
- 40 m³ and 9,000 kg: a 20ft takes 28.1 usable m³, too little. A 40ft takes 57.4 m³: 70 % volume and 34 % payload, so one 40ft.
- 18 m³ of stone tiles weighing 27,000 kg fits one 20ft by both volume (64 %) and payload (96 %); a 40ft would not carry more weight.
Questions and answers
When is a 20ft container better than a 40ft?
For heavy, dense cargo such as tiles, metal or liquids in drums. A 20ft carries about as much weight as a 40ft for less money, and up to about 28 m³ of cargo.
How much cargo fits in a 40ft container?
About 67 m³ of inside volume, of which 55–58 m³ is realistic to fill, and up to about 26,700 kg. A 40ft High Cube adds 30 cm of height, roughly 76 m³ inside.
Why plan with 85 % of the volume?
Packages rarely fill corners, the door end and the space under the roof exactly. 85–90 % is the rule of thumb forwarders use; bulky mixed cargo may reach less.
Is one 40ft cheaper than two 20ft containers?
Usually yes for volume cargo, since a 40ft costs much less than two 20ft. For heavy cargo two 20ft containers may be needed because a 40ft cannot carry twice the weight.
What is the difference between 40ft and 40ft High Cube?
The same length and width, but the High Cube is 30 cm taller inside (269 vs 239 cm). It helps with tall or stackable cargo.
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