Shipping Container Dimensions, Types and Corner Casting Guide: A Complete Reference to ISO 668

Shipping containers are the fundamental load units handled by container cranes, rubber-tyred gantry (RTG) cranes, rail-mounted gantry (RMG) cranes, ship-to-shore (STS) cranes, reach stackers, and other port handling equipment. Understanding shipping container dimensions, ISO size-type codes, corner casting centre distances, and the differences between ISO Series 1 and China’s Series 2 inland containers is essential for designing and selecting spreaders, twist-lock systems, lifting attachments, and container handling machinery. This guide covers the most common container sizes from 20ft to 50ft, explains corner casting geometry and twist-lock spacing, and provides the four-character size-type code system defined by ISO 668 and GB/T 1413 to support safe, efficient container lifting operations.

Containers are categorised by length — 20ft, 40ft, and 45ft are the most common — with 10ft, 30ft, 8ft, 50ft, 53ft (North American inland), and 63ft containers seeing more limited use. By type they are classified as dry freight, refrigerated (reefer), open-top, flat-rack, tank, and ventilated containers. By structure they can be fixed or collapsible; by material, steel or aluminium.

1. 20ft General Purpose Container (GP)

Standard external dimensions: length 6,058 mm (20ft), width 2,438 mm (8ft), height 2,591 mm (8ft 6in).

The workhorse of global container shipping. Suitable for heavy or general cargo — ore, machinery, cast iron parts, fitness equipment, flexitanks, electronics, and consumer goods. Used across ocean, rail, and road transport.

• Rated gross mass generally ≤ 21 t
• Usable internal volume approx. 28–31 m³
• Max. laden weight approx. 28 t, payload approx. 26 t, tare approx. 2.2–2.5 t

2. 40ft General Purpose Container (GP)

Standard external dimensions: length 12,192 mm (40ft), width 2,438 mm (8ft), height 2,591 mm (8ft 6in).

The dominant container in international trade, especially ocean freight. Suited for large cargo — furniture, appliances, machinery.

• Rated gross mass generally ≤ 24.5 t
• Usable internal volume approx. 63–66 m³
• Max. laden weight approx. 30.48 t, payload approx. 26 t, tare approx. 3.8–4.2 t

3. 40ft High Cube Container (HC / HQ)

Standard external dimensions: length 12,192 mm (40ft), width 2,438 mm (8ft), height 2,896 mm (9ft 6in).

The extra 305 mm (1 ft) of internal height makes this container ideal for tall cargo — steel sections, timber — and volume-constrained loads.

• Rated gross mass generally ≤ 22 t
• Usable internal volume approx. 68–76 m³
• Max. laden weight approx. 30.48 t, payload approx. 26 t, tare approx. 3.8–4.2 t

4. 45ft High Cube Container (HC)

Standard external dimensions: length 13,716 mm (45ft), width 2,438 mm (8ft), height 2,896 mm (9ft 6in).

The largest standard ISO Series 1 container. Due to its size and weight, transport stability demands extra attention.

• Rated gross mass generally ≤ 29 t
• Usable internal volume approx. 68–76 m³
• Max. laden weight approx. 34.02 t, payload approx. 29 t, tare approx. 4.7–4.8 t

Corner Casting Centre Distances — Twist-Lock Geometry

Corner castings are the primary interface for container lifting, transfer, and securing. The twist-lock centre distances for common 20ft, 40ft, and 45ft containers are given in Tables 1 and 2.

A key design detail: the 45ft container has corner castings at both the 40ft position (11,985 mm centre-to-centre) and the full 45ft position (13,509 mm). This means a 45ft container can be handled by a standard 40ft spreader — the 40ft-position castings are used for stacking and securing with 40ft stacks, while 45ft-capable spreaders extend pins to the full 13,509 mm centres.

Shipping Container Dimensions-Type Codes

Container models are designated by a four-character code. For length codes: 40ft = A, 30ft = B, 20ft = C, 10ft = D, 45ft = E. This is combined with a height code — for example, a 45ft general purpose container is coded 1EE or 2EE, where “1” = Series 1 (international intermodal) and “2” = Series 2 (inland multimodal). See Tables 3–7 for full coding.

Series 1 containers are intended for international intermodal transport; Series 2 containers are designed for inland multimodal transport within China. The classification structure is essentially the same.

Common Railway Container Models and Dimensions (China)

Container Structure

A container is built from corner castings, cross members, corner posts, and floor structures, together with the roof, floor panel, side panels, and door assemblies.

Quick reference:

1. A “20ft container” does not mean the container is physically 20 feet long — it refers to the ISO modular unit. A 40ft container = 2 TEU (twenty-foot equivalent units).
2. Unit conversions: 1 ft = 30.48 cm, 1 in = 2.54 cm, 1 ft = 12 in.

Reference Standards(Query of Chinese Crane Standards):

• GB/T 1413-2023 Series 1 freight containers — Classification, dimensions and ratings (IDT ISO 668:2020)
• GB/T 35201-2017 Series 2 freight containers — Classification, dimensions and ratings
• GB/T 1992-2023 Freight containers — Vocabulary (MOD ISO 830:1999)
• GB/T 17382-2023 Series 1 freight containers — Handling and securing (IDT ISO 3874:2017)
• GB/T 1835-2023 Series 1 freight containers — Corner fittings specification (MOD ISO 1161:2016)
• GB/T 3220-2011 Freight container spreader
• JT/T 1173-2017 Series 2 freight container spreader — Dimensional and lifting requirements
• JT/T 1172.1-2017 Series 2 freight containers — Specification and testing — Part 1: General cargo containers

krystal

Crane OEM expert

With 8 years of experience in customizing lifting equipment, helped 10,000+ customers with their pre-sales questions and concerns, if you have any related needs, please feel free to contact me!

WhatsApp: +86 199 1373 9708

Email: krystalli@kscranegroup.com