Tonnekilometers

Tonnekilometer, abbreviated tonne-kilometre or tonne-km, is a unit of measurement used in freight transport to quantify the amount of work performed. One tonne-kilometre equals transporting one tonne (one metric ton) over a distance of one kilometre. In formula terms, it is the product of load mass (tonnes) and distance traveled (kilometres).

Calculation and examples: If a truck carries 20 tonnes for 150 kilometres, the work done is 20 × 150 = 3,000 tonne-kilometres. A shipment of 5 tonnes over 2,000 kilometres equals 10,000 tonne-kilometres. The unit can be summed across multiple trips or modes to yield total freight activity.

Usage and purpose: Tonnekilometres are used to aggregate and compare freight movements, to normalize indicators such as energy consumption or emissions per transport distance and load, and to analyze efficiency across modes (road, rail, sea, air). The measure focuses on transport work rather than cost, speed, or value of goods.

Relation to other measures: The imperial counterpart is tonne-mile. Tonnekilometres are often used in statistical reports and sustainability analyses to express performance in terms of work performed, such as energy intensity (megajoules per tonne-km) or emissions intensity (CO2 per tonne-km).

Limitations: The unit does not reflect cargo value, shipment density, or the distribution of distances within a transport chain. It also does not account for empty backhauls or variations in load factor; two shipments with the same tonne-km can have very different economic or logistical characteristics.

Modes: All freight modes contribute to tonne-km totals, with differences in typical tonne-km per trip reflecting distance, load capacity, and network structure.