Container Types Explained

Learn about the main shipping container formats, 20DC, 40DC, 40HC, and specialised types including reefer, open-top and flat-rack containers.

20ft Standard (20DC)

The most common container format worldwide. 33.2 m³ internal volume, 28,280 kg payload. Ideal for heavy cargo, general freight and short-haul operations.

40ft Standard (40DC)

Double the length of a 20DC with 67.7 m³ volume. Used for high-volume shipments where weight is not the limiting factor.

40ft High Cube (40HC)

30 cm taller than a 40DC providing 76.3 m³ volume. The preferred unit for voluminous cargo and SOC one-way leasing.

Specialised Types

Reefer containers for temperature-controlled cargo. Open-top for oversized loads. Flat-rack for heavy machinery. Tank containers for liquids.

What are the main types of shipping containers used in maritime trade?

The container industry uses six main types, each optimised for a specific cargo profile. Dry containers (DC) are the standard general-purpose box, what most people picture when they think "shipping container". High Cube (HC) is the same as DC but one foot taller, dominant for volume-driven cargo. Reefer (RF) is a refrigerated container with active temperature control, for perishables. Open Top (OT) has a removable tarpaulin roof instead of a fixed top, for over-height or top-loaded cargo. Flat Rack (FR) has collapsible end walls and no sides, for oversized or heavy machinery. Tank is a stainless-steel cylinder inside a standard frame, for bulk liquids. Each type follows ISO dimensional standards so they're all interchangeable in vessel slots and on chassis.

Dry (DC) and High Cube (HC) what's the difference and when to use each?

DC and HC are the workhorses of the industry, they account for the vast majority of global container moves. The only physical difference is height: a DC is 8'6" tall externally (2.591 m), an HC is 9'6" (2.896 m). Same length, same width, same payload capacity, same vessel slot footprint. The HC's extra foot translates to roughly 13% more internal volume for the same external footprint. Choose DC for dense, weight-heavy cargo (machinery, metals, liquids in drums) where the extra cube would go unused. Choose HC for light, voluminous cargo (furniture, textiles, packaged goods) where the extra height lets you stack a second tier of pallets.

Reefer (RF) what makes a refrigerated container different?

A reefer is a fundamentally different piece of equipment. It carries an integrated refrigeration unit (powered by ship's mains or a generator on land), insulated walls, an air-circulation T-bar floor, and a controlled atmosphere capability on some units. Temperature range typically -30°C to +30°C with precision around ±1°C. Reefers are used for perishables: meat, fish, fruit, vegetables, pharmaceuticals, certain chemicals. They cost roughly 3 to 5 times more than a dry container to buy and significantly more to ship because of the power requirement at every leg. Reefer-grade certification is separate from CSC and includes annual PTI (Pre-Trip Inspection) testing. Reefers aren't interchangeable with dry containers for cargo purposes, if your cargo doesn't need controlled temperature, a reefer is over-spec.

Open Top (OT), Flat Rack (FR), and Tank, when do you actually need them?

These three special equipment types handle cargo that doesn't fit a closed standard box. Open Top has a removable tarpaulin roof for over-height items (industrial machinery, processed timber, glass sheets stacked high) that can't be loaded through normal end doors. Flat Rack is essentially a base with collapsible end walls, used for project cargo: turbines, large vehicles, boats, prefab steel structures. The cargo is tied down on the deck, often exceeding container width. Tank containers carry bulk liquids (chemicals, food-grade liquids, fuel) inside a stainless-steel vessel framed to ISO dimensions. All three are specialist equipment with limited availability and higher daily rates than dry, only use them when standard dry won't fit the cargo.

Which container type should I choose for my cargo?

Three filters cover most decisions. (1) Does the cargo need temperature control during transit? Yes → reefer. No → continue. (2) Does the cargo fit through the standard 2.34 m × 2.28 m end doors of a DC, with reasonable headroom inside? No, it's too tall or too wide → Open Top or Flat Rack. Yes → continue. (3) Is the cargo dense and heavy, or light and voluminous? Dense and heavy → 20DC. Light and voluminous → 40HC. Liquid in bulk that needs no temperature control → tank or IBC-loaded DC depending on volume. Most dry cargo lands on 40HC by default; 20DC for heavy or dense loads; reefer for perishables; specials only when standard formats genuinely don't fit.