A single twenty-foot equivalent unit is the capacity of a standardized twenty-foot long shipping container
In common use, the twenty-foot equivalent unit (or TEU) is a measure of shipping capacity based upon the volume of a standard twenty-foot long by eight-foot wide by about 8.5-foot tall metal container. The unit is useful measuring shipping capacity at all levels of the shipping/cargo industry including a single ship, a train, an entire fleet of ships, a shipping company, or entire port of commerce.
It should be noted that the number's derivation relative to shipping volume is inexact for two primary reasons:
- The volume of the containers, in practice, does not typically correlate to the amount of product that can be shipped, as many objects may necessitate an entire container but come far from filling it to capacity. For example, one could likely fit two mid-sized cars into a single twenty-foot container, but they would hardly occupy the entire volume of the container.
- The height of the metal containers used in shipping is highly variable (from 4 feet to 9 feet tall). Ultimately, the height of the container used is dependent more upon the shipping needs than any standard practices.
Further, shipping containers come in myriad sizes and lengths to facilitate large and odd-sized cargo. For example, a ship may need to utilize a container 45 feet long to transport a particularly large piece of cargo. This container would be classified as 2 or 2.25 TEUs (depending on the exactitude of the measurement).
The metric is used primarily in the shipping industry to measure and compare total shipping capacity between companies. Round numbers giving approximations of scale (rather than exact numbers of minutia) are typically preferred as, again, the metric is non-exact.
