Overview
ISO 668:2020 - Series 1 freight containers - Classification, dimensions and ratings - defines the external classification, key external dimensions, permissible tolerances and gross-mass ratings for Series 1 containers intended for intercontinental traffic. It summarizes external and some internal dimensions (width, nominal lengths, heights), specifies measurement reference conditions and identifies mandatory/optional features (for example gooseneck tunnels). The authoritative internal-dimension details for each container type remain in the relevant parts of ISO 1496.
Key topics and requirements
- Classification by external dimensions: Series 1 containers have a uniform width of 2 438 mm (8 ft) with nominal lengths including 45 ft, 40 ft, 30 ft, 20 ft and 10 ft, and height classes of 2 896 mm (9 ft 6 in), 2 591 mm (8 ft 6 in), 2 438 mm (8 ft) and smaller heights (designated “X”).
- Ratings (maximum gross mass, R): Tableed ratings apply to container types; many Series 1 types show an R of 30 480 kg (67 200 lb) while smaller types have lower ratings (see standard for exact values). Higher ratings are permissible for special traffic but ISO conformity requires proper testing and marking and R ≤ 36 000 kg to be treated as ISO containers.
- Internal and door opening dimensions: Minimum internal and door-opening dimensions are provided (with references to ISO 1496 series for detailed internal geometry). Top corner fittings projecting into the interior are handled explicitly.
- Tolerances and measurement conditions: Dimensions and tolerances apply at a reference temperature of 20 °C; adjustments are required for other temperatures.
- Mandatory features and annexes:
- Gooseneck tunnels mandatory for certain tall types (e.g., 1EEE, 1AAA) - Annex C.
- Corner fitting locations and tolerances - Annex A.
- Load-transfer/base structure requirements - Annex B.
Applications and who uses it
ISO 668:2020 is essential for:
- Container manufacturers specifying external framing, corner fittings and ratings.
- Shipping lines, port operators and intermodal carriers ensuring worldwide interchangeability and safe handling.
- Chassis, trailer and railcar designers for vehicle/container interface compatibility.
- Freight forwarders and cargo planners to verify cargo fit (door openings, internal clearances).
- Inspection bodies and regulatory authorities for testing, marking and conformity assessment.
- Equipment and terminal automation vendors integrating container dimensions into handling systems.
Related standards
- ISO 1496 (series) - authoritative internal-dimension and type-specific requirements (general purpose, thermal, tank, etc.).
- ISO 6346 - container coding, identification and marking.
- ISO 830 - freight container vocabulary and definitions.
Keywords: ISO 668:2020, Series 1 freight containers, container dimensions, container classification, container ratings, intermodal, gooseneck tunnel, corner fittings, ISO 1496.
