What is a TEU (twenty-foot equivalent unit)?
TEU is how the container industry measures capacity and volume: the size of a ship, the throughput of a port, a carrier's service contract or a forwarder's yearly business. The largest container ships have capacities above 20,000 TEU. A 40-foot container is also called an FEU, a forty-foot equivalent unit, and 45-foot boxes are usually counted as two TEU as well, although conventions vary.
A TEU is a counting unit, not an exact volume or weight. A 40-foot high cube counts as two TEU like a standard 40-foot, even though it holds about 76.4 m³ inside against 67.7 m³. A ship's nominal TEU capacity is also higher than the number of loaded containers it can actually carry, because weight and stability limit how many heavy boxes fit on board.
Freight rates, surcharges and contract volume commitments are often stated per TEU or per FEU, so convert before comparing. Counting in TEU also makes mixed volumes comparable: a forwarder that shipped ten 20-foot and five 40-foot containers in a month moved 10 + 5 × 2 = 20 TEU. It is the usual figure for reporting volume to carriers and partners.