The decision, with numbers
20 ft vs 40 ft Container
The forty is not “a bigger twenty” — it is a different tool. The 20 ft is a weight carrier: 28 t of payload wrapped in 33 m³. The 40 ft is a volume carrier: double the space, marginally less weight allowance.
Side by side
Three things jump out of the table. Width and height are identical — 2.438 m and 2.591 m external on both, so anything that fits through one door fits through the other. Volume exactly doubles: 33.2 to 67.7 m³, because the only dimension that changes is length. And payload barely moves — 28,250 kg vs 26,740 kg — because both boxes share the same 30,480 kg max gross rating and the longer one spends ~1.5 t more of it on its own steel.
| 20 ft container | 40 ft container | |
|---|---|---|
| ISO type code | 22G1 | 42G1 |
| External dimensions — Length | 6.058 m19′11″ | 12.192 m40′ |
| External dimensions — Width | 2.438 m8′ | 2.438 m8′ |
| External dimensions — Height | 2.591 m8′6″ | 2.591 m8′6″ |
| Internal dimensions — Length | 5.898 m19′4″ | 12.032 m39′6″ |
| Internal dimensions — Width | 2.352 m7′9″ | 2.352 m7′9″ |
| Internal dimensions — Height | 2.393 m7′10″ | 2.393 m7′10″ |
| Tare weight | 2,230 kg4,916 lb | 3,740 kg8,245 lb |
| Max gross weight | 30,480 kg67,197 lb | 30,480 kg67,197 lb |
| Max payload | 28,250 kg62,281 lb | 26,740 kg58,952 lb |
| Capacity (volume) | 33.2 m³1,172 ft³ | 67.7 m³2,391 ft³ |
| EUR pallets | 11 | 25 |
| TEU | 1 | 2 |
The economics
Ocean pricing typically puts the 40 ft at 1.3–1.6× the 20 ft rate — not 2×. Per cubic metre, the forty is therefore 20–35% cheaper. Once your cargo passes roughly 25–28 m³, stepping up to a 40 ft usually wins even if you sail with empty space.
The reverse rule: if your cargo density exceeds ~850 kg per m³ (tiles, paper, metal, liquids), a 20 ft hits its weight ceiling before a 40 ft would even be half full — pay for the smaller box, or split across two twenties to stay road-legal at destination.
When the answer is neither
Cargo taller than 2.39 m → 40 ft high cube. Maximum EUR pallet count in Europe → 45 ft pallet-wide. Under ~15 m³ → LCL (shared container) is usually cheaper than any dedicated box.
Frequently asked questions
Is a 40 ft container cheaper than two 20 ft?
Almost always for the same total volume — one 40 ft typically costs 1.3–1.6× a single 20 ft rate, versus 2× for two twenties, and you pay one set of handling and customs fees instead of two.
Why does a 20 ft container carry more weight than a 40 ft?
Both share ratings near 30,480 kg max gross, but the 40 ft box itself weighs ~1.5 t more, eating into payload. Structural floor-strength per metre also favours the shorter box for concentrated loads.
Is it better to ship two 20 ft containers or one 40 ft?
For the same volume, one 40 ft is cheaper per CBM — one freight rate at 1.3–1.6× the 20 ft price, one set of handling and customs fees. Two twenties win in two cases: cargo that is weight-limited (above ~28 t total needs two boxes anyway) and shipments splitting to different destinations.