Hong Life CalculatorsUnderstanding the shipping container volume chart — concept and principle
Freight is quoted and planned in cubic meters (CBM), and the first question in any shipment is which container size fits the cargo. This chart gives the typical inside length, width and height of standard ISO dry containers (20ft, 40ft, 40ft high cube and 45ft high cube), the resulting internal volume and an approximate maximum payload, so you can estimate whether your goods need a full container (FCL) or can share one (LCL).
How it is calculated
Internal volume is the product of the three inside dimensions:
V = L × W × H (m³).
The chart lists typical values for each type; the payload column is an approximate figure, because the real limit depends on the box's tare weight and its rated maximum gross mass.
The principle
ISO 668 fixes the external sizes of freight containers so that they stack and lock together on ships, trains and trucks: a 20ft box is about 6.058 m long, 2.438 m wide and 2.591 m high, and a high cube is about 2.896 m high. Walls, floor and corrugated steel take up space, so inside dimensions are smaller and vary slightly between manufacturers. The 20ft box defines the TEU (twenty-foot equivalent unit) used to measure ship and port capacity; a 40ft box counts as 2 TEU.
Worked example
Default: 20ft dry.
- Inside dimensions: 5.898 × 2.352 × 2.393 m.
- Volume: 5.898 × 2.352 = 13.872 m²; × 2.393 = 33.196 m³, shown as 33.2 m³.
- Approximate maximum payload: ≈ 28,000 kg.
For comparison, a 40ft dry gives 12.032 × 2.352 × 2.393 = 67.7 m³, and a 40ft high cube gives 76.4 m³.
How to read the result
Theoretical volume is never fully usable, because cartons and pallets leave gaps. A 20ft box is often loaded with about 25–28 m³ of cartons and a 40ft with about 55–60 m³. Check weight as well as volume: dense goods such as tiles, steel or paper reach the weight limit long before the box is full, so they usually go in 20ft containers, while light, bulky goods favor 40ft high cubes. Road weight limits in the origin and destination countries can be lower than the container's own rating.
Common mistakes
- Planning with the full internal volume instead of a realistic loading volume.
- Forgetting the door opening, which is smaller than the inside cross-section and limits tall or wide items.
- Ignoring pallet footprint: pallet sizes may not tile the 2.35 m width efficiently.
- Assuming every 20ft box has the same payload; read the plate on the container door.
FAQ
Frequently asked questions
How many CBM fit in a 20ft container?
About 33.2 m³ inside, usually about 25–28 m³ in practice.
How many CBM fit in a 40ft high cube?
About 76.4 m³ inside; the extra 0.3 m of height suits light, bulky cargo.
When is LCL cheaper than a full container?
For small volumes it often is, but the break-even point depends on current rates, so compare quotes.
Sources: ISO 668 Series 1 freight containers – Classification, dimensions and ratings · ISO 1496-1 Series 1 freight containers – Specification and testing – Part 1: General cargo containers