The largest container ships now haul more than 24,000 steel boxes at once

A single modern container ship can now carry more cargo boxes than existed in most entire ports just a few decades ago. The largest vessels afloat move upward of 24,000 twenty-foot equivalent units, the shipping industry’s standard measure for cargo capacity, on a single voyage, a scale of freight that has reshaped port design, canal engineering, and global supply chains far beyond the shipping industry itself.

Reaching that number took more than sixty years of steady growth in vessel size, driven by a straightforward economic logic: a bigger ship can move more cargo per crew member, per gallon of fuel, and per hour of port time, which keeps pushing shipbuilders toward ever larger hulls.

Measuring Cargo in Steel Boxes

The twenty-foot equivalent unit, or TEU, standardizes container capacity around the dimensions of a basic shipping container, letting vessels of wildly different designs be compared on equal terms. Most modern container ships actually carry a mix of twenty-foot and forty-foot boxes, but industry figures are consistently expressed in TEU so that a ship’s stated capacity reflects a theoretical maximum rather than any single real-world loading configuration. That standardization, which also underpins how ports plan crane capacity and how railways and trucking networks schedule inland cargo movement, is part of why containerized shipping became the dominant method of moving manufactured goods around the world in the first place.

The Vessels Currently at the Top

Among the ships built specifically to push capacity limits, Evergreen Marine’s A-class vessels, including the Ever Alot, carry a stated capacity of 24,004 TEU, a figure that briefly made it the largest container ship in the world when it entered service. That record did not last, as MSC’s Irina-class ships followed with a capacity of 24,346 TEU, becoming the new benchmark as of early 2024. Vessels in this size class typically stretch around 400 meters in length and roughly 61 meters in beam, dimensions that push right up against the physical limits of the world’s largest ports and shipping canals rather than being constrained by engine power or hull strength alone.

Where These Giants Get Built

Ships in the 24,000-TEU class come from a small number of shipyards capable of the precision and scale the work requires. South Korea’s Samsung Heavy Industries has built several vessels in this class, while China State Shipbuilding Corporation has constructed others at yards across the country, reflecting how concentrated the capability to build ultra-large container ships has become among a handful of East Asian shipbuilders. Placing an order for a ship at this scale typically involves years of lead time and a construction process that rivals major infrastructure projects in complexity, since the vessel’s propulsion, ballast, and structural systems all have to be engineered for loads that did not exist in commercial shipping a generation earlier.

Ports and Canals Had to Catch Up

Building the ships turned out to be only half the challenge, since a vessel this large is useless without a port capable of loading and unloading it. Major ports have spent billions of dollars deepening berths, installing taller cranes with longer reach, and widening approach channels specifically to accommodate vessels in the 24,000-TEU class, upgrades that smaller and less-funded ports simply cannot afford to make. The same pressure has forced infrastructure decisions at major canals, where lock and channel dimensions effectively cap how large a ship can get before it becomes physically unable to use that route at all, pushing some of the largest vessels onto longer alternative paths between major shipping regions.

What Happens When One of These Ships Gets Stuck

The same scale that makes these ships economically efficient also makes their occasional failures unusually disruptive. A grounding, mechanical breakdown, or collision involving a vessel carrying tens of thousands of containers can back up shipping traffic across an entire waterway for days, since narrow canals and channels typically have no way to route around a stranded ship of that size. Insurers and cargo owners have increasingly had to factor in the possibility that a single incident involving one of these vessels could delay deliveries across dozens of unrelated supply chains simultaneously, simply because so much cargo now travels concentrated on so few, very large hulls rather than spread across a larger number of smaller ships.

Why Size Keeps Climbing

The economic case for bigger ships has remained consistent even as individual vessels have grown to the edge of what infrastructure can support. Carrying more containers per voyage spreads fuel and crew costs across a larger cargo load, lowering the per-container cost of moving goods across an ocean, which is the same logic that has driven container ship capacity upward since the earliest purpose-built container vessels entered service decades ago. According to the container ship’s own operating history, that growth has been remarkably steady rather than sudden, with each new size class typically arriving a few years after the last record holder. A running tally of exactly which vessels currently hold the largest-capacity distinction is maintained in the list of the largest container ships ever built, a ranking that has changed hands several times in just the past few years as shipbuilders continue testing how much bigger the format can practically get.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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