The cubic metre (symbol m³) is the International System of Units (SI) derived unit for volume. By definition it is the volume of a cube whose edges each measure one metre. The unit is commonly written as "cubic metre" or, in American English, "cubic meter" and the recommended SI notation uses the superscript form m³.
Definition and common equivalents
One cubic metre equals 1,000 litres (1 m³ = 1,000 L) and 1,000,000 cubic centimetres (1 m³ = 1,000,000 cm³). Because the litre is a non-SI unit accepted for use with SI, references to the litre are frequent; see the SI overview at SI units and the litre entry at litre.
Characteristics and practical relations
- Geometric meaning: a cube 1 m × 1 m × 1 m.
- Mass relation: approximately 1,000 kilograms of pure water at typical temperatures (often rounded to 1 tonne per m³).
- Alternate names: kilolitre (kL) is numerically equal to 1 m³; stère has been used historically for stacked firewood but is not an SI unit.
- Common non‑SI abbreviation: "cbm" or "CBM" appears in shipping and logistics though it is not an SI symbol.
History and usage
The cubic metre arose naturally with the adoption of the metre as the base unit of length in the metric system during the 19th century and was formalized as the SI unit of volume with the creation of the SI. It is widely used in engineering, construction, shipping, fluid flow and resource reporting (for example natural gas and water volumes).
Examples and distinctions
Practical examples: a small garden shed might be 12 m³, a typical 20-foot shipping container offers roughly 33 m³ of internal volume, and a room 2 m × 3 m × 4 m contains 24 m³ (24,000 L). Important distinctions include correct notation (space between number and unit, e.g. "5 m³") and awareness that names like "stère" or abbreviations like "cbm" are non‑SI and may be used in specific trades or regions.