Types of Shipping Containers

1. Does the cargo need to be weatherproof? If it can ride exposed under a tarpaulin or lashed to a platform — machinery, steel, timber, anything craned in from above — you are looking at an open top or a flat rack, and the rest of the decision tree does not apply.

2. Does it need temperature control? Cargo that must hold a setpoint — frozen food, pharmaceuticals, chemicals with a narrow band — needs the active machinery of a reefer. Cargo that only needs protection from swings and condensation — chocolate, wine, electronics, coffee — is served passively by an insulated or ventilated box, at a fraction of the cost.

3. Does it fit the standard envelope, and is it solid? Liquids and gases in bulk go in a tank container. Loads wider than a dry box’s 2.352 m inside, or heavier than the 28,250 kg a dry 20 ft carries, ship as out-of-gauge (OOG) on a flat rack. Everything else — which is most of world trade — ships in a dry or high cube box.

Dry (22G1/42G1). The general-purpose box that defines the fleet: corrugated steel walls, plywood floor, double doors at one end. It carries anything solid, dry and box-shaped, which is most of what is shipped. Key figures: 33.2 m³ and a 28,250 kg payload (20 ft), or 67.7 m³ and 28,800 kg (40 ft). Best for: cartons, pallets, machinery in crates — the default answer. Full specs: 20 ft and 40 ft.

High cube (45G1). The same box stretched one foot taller — 2.896 m external, 2.698 m inside — which buys 76.4 m³ in the 40 ft format, 13% more than standard height. Best for: volumetric cargo — furniture, apparel, e-commerce goods — and conversions that need ceiling height. Full specs: high cube and 40 ft HC.

Reefer (22R1/45R1). An insulated box with a built-in refrigeration machine holding a setpoint from +30 °C down to −30 °C (−40 °C on some units, as the machine makers’ and Hapag-Lloyd’s sheets print), powered from ship, terminal or a clip-on genset. The machinery and insulation cost volume and weight: 28.3 m³ (20 ft) and 67.5 m³ (40 ft HC), tare 2,980 and 4,620 kg. Best for: frozen and chilled food, fruit under controlled atmosphere, pharmaceuticals. Full specs: reefer container.

Open top (22U1/42U1). A dry box with the steel roof replaced by removable bows and a tarpaulin, so cargo loads by crane from above instead of forklift through the doors. Hapag-Lloyd’s sheet prints roof openings of 5.34–5.42 × 2.23 m on the 20 ft and 11.55–11.57 × 2.21–2.23 m on the 40 ft. Best for: machinery, glass in racks, timber, over-height pieces that stand proud of the roofline. Full specs: open top.

Flat rack (22P1/42P1). No roof, no walls — just a heavy platform with fixed or collapsible end bulkheads and lashing points rated in tonnes. Decks measure 5.636 × 2.194 m (20 ft, payload 31,060 kg) and 11.652 × 2.374 m (40 ft, payload 40,000 kg on a 45,000 kg max gross), length between the corner posts and width over the side rails. Best for: transformers, boats, construction plant, anything over-width or over-weight. Full specs: flat rack.

Tank (22T1). A stainless-steel pressure vessel, most often 25,000 L (the sheets we read print 20,000–26,000 L), held in a standard 20 ft frame, so a bulk liquid handles exactly like a box. The UN portable-tank instruction on its plate says what it may carry: T1 to T22 for liquids and solids, T50 for liquefied gases under pressure, T75 for refrigerated liquefied gases. A stricter tank may carry what a lighter instruction is assigned, never the reverse: a substance assigned T11 may also travel in a T12–T22 tank (UN Model Regulations, 4.2.5.2.5). Best for: chemicals, food-grade liquids, fuels. Full specs: tank container.

How each type is loaded, what it does about temperature, and the volume and payload of each length where carriers publish one. Every size of the dry and high cube boxes, inside and out, is in the dimensions chart.

Three variants change nothing about the box except how you get in. Double door (tunnel) repeats the standard 2.340 × 2.280 m door set at both ends, so a forklift drives through, long cargo loads from either side, and a converted unit gets two entrances. Its tare stays close to a standard box’s (about 2,200 kg for a 20 ft); the second door frame takes about 54 mm of inside length.

Open side replaces one long wall of a 20 ft with bi-fold doors, opening 5.70–5.83 m of the side on Bullbox’s and Sea Box’s sheets — nearly the full 5.898 m inside length. Every pallet position becomes directly forklift-accessible, which is why market stalls, pop-up bars and on-site workshops favour it. Hard top is an open top with a removable steel roof panel instead of bows and tarpaulin: the panel lifts off by crane in one piece, survives repeated cycles that would shred a tarp, and carries roof loads when refitted. Both are niche builds priced well above a standard dry box.

Ventilated (VH codes). A dry box with fixed gallery vents along both the top and bottom side rails, creating a passive chimney of airflow through the cargo. It exists for goods that breathe — green coffee and cocoa above all, hence the nickname “coffee container” — where a sealed box would condense moisture onto the beans mid-ocean. Why that happens, and what vents can and cannot fix, is covered in our ventilation and condensation guide.

Insulated. The opposite philosophy: seal the box and slow heat transfer with insulated walls — no refrigeration machine, no power. The thermal mass smooths day–night swings and buys days of drift instead of hours, which suits cargo that must avoid shocks rather than hold a setpoint: wine, chocolate, electronics. Retired reefers with the machinery removed serve the same role cheaply. Wall build-ups and achievable R-values are in the insulation guide.

Half-height. An open-top box 1.295 m (4 ft 3 in) tall — the height ISO 6346 codes as 8 in the second character — on a standard 20 ft footprint. Dense cargo — ore, aggregates, steel billets — reaches a 20 ft’s weight limit at a fraction of a full box’s volume, so the missing height costs nothing and the low walls make excavator loading and tipping far easier. Two stacked half-heights occupy one standard slot.

Bulk (BU). A sealed dry box with two or three loading hatches in the roof and a discharge hatch in the door, so grain, malt or plastic granulate pours in by gravity and out by tipping — no bags, no big-bags, no pallets. Its volume is close to a dry 20 ft’s 33.2 m³; the saving is entirely in handling time.

Platform (P0). A flat rack with even the end walls deleted: a bare 6.058 or 12.192 m floor with corner castings and lashing rings. It exists for super-heavy and super-long pieces — several platforms lash together side by side under one indivisible load that no walled container could accept.

GOH (garments on hangers). A standard dry box fitted with removable string or bar systems across the ceiling, so finished clothing travels hanging and rolls straight from container to shop floor without a pressing step. The fashion trade runs entire seasonal fleets of them; unstrung, the box reverts to ordinary dry service.

Pallet-wide. A European variant widened to 2.500 m externally for 2.444 m inside (CMA CGM’s sheet) — enough for two 1.2 m EUR pallets side by side, lifting a 45 ft unit from 27 to 33 EUR pallets. Intra-European short-sea and rail runs on them; deep-sea cells do not always accept the extra width. See the 45 ft container page.

Tricon and Quadcon. Military and expedition boxes one-third and one-quarter the length of a 20 ft slot, at the full ISO width. Three Tricons or four Quadcons pin together into one 20 ft footprint and ship as 1 TEU, then break apart for helicopter or truck moves at the far end.

Swap body. A European road/rail exchange box, longer than a 20 ft box and pallet-wide inside, with fold-down legs so a truck can drive out from under it. It has bottom castings but no top-lift fittings and cannot be stacked loaded — which is why it never goes to sea, and why it is cheaper and lighter than any ISO box.

The last two characters of the size/type code on every container door encode exactly what the box is — the full four-character system is decoded in our ISO standards guide. The letters worth recognising: