How many containers fit on a ship?
Last Updated on August 18, 2023
It’ll come as no surprise to learn that shipping containers arrive by way of – you guessed it – ships! It’ll probably be no less of a surprise to discover that we are regularly asked, and Google is regularly asked, “Just how many containers fit on a ship?” If you were expecting a straightforward answer, we’re sorry to say that there isn’t one. Instead, the number of containers which fit on a ship will depend on a variety of factors that relate to both the ship and the containers themselves. To provide a more thorough explanation of this dynamic, and to help give you a rough idea of how many containers typically travel together, we’ve broken down the variables which will determine how many containers will fit on a ship.
Naturally, it makes practical sense to transport as many containers as possible heading in the same direction in one load. To this end, many cargo vessels have been optimised by shipping companies to bear impressive weights on the water. Though they come in a range of shapes and sizes, the most popular types of container ships are Panamax, Post-Panamax, and Ultra Large Container Vessels, more commonly referred to as ULCVs. The first of these, Panamax ships, are named due to their design being based on the need to pass through the locks of the Panama Canal. With a not-unimpressive capacity of around 4,000 to 5,000 TEUs (that’s “Twenty-foot Equivalent Units” to the layman, and to make things even more interesting, a 20ft container is actually 19ft 10.5in long, though is still known as a TEU), these vessels provide a useful idea of the size of container ships at the smaller end. The second variant, the Post-Panamax vessel, cannot pass through the Panama Canal but is capable of carrying 12,000 TEUS, double that of the smaller model of container ship. At the extreme end of the scale, ULCVs can accommodate up to around 20,000 TEUs, though it is not unusual for some to carry 24,000 TEUs.
Following everything so far? Good, because things are about to get even trickier when it comes to answering the question of how many containers fit on a ship. Whilst it might seem reasonable enough to assume that if a ULCV is capable of carrying up to 24,000 TEUs then the answer is “Well, up to 24,000 containers can fit on a ship”. Frustratingly, things aren’t that simple.
Remember how the measurement of TEUs referred to twenty-foot equivalent units? Well, this measurement isn’t without its own set of complications. The first reason that this measurement is complicated is that it is an inexact unit of cargo capacity rather than an exact and dependable one. Whilst it is based on the volume of a 20-foot-long (6.1m) standard-sized container, its height is not standardised and can range anywhere from 4.3 feet to 9.6 feet. With this variance in mind, it quickly becomes obvious that how many containers fit on a ship will be determined by the makeup of the load that needs transporting.
As you might expect, shipping companies are complete pros when it comes to arranging an assortment of different shipping containers and there are designated planners the world over who ensure that transport is carried out in the most efficient way possible. By stacking and arranging them in patterns, carriers are able to utilise the space they have available to them and ensure that they are able to travel as efficiently as possible. This is made even easier by the cell guides that are common to many container ships that provide vertical structures which help to guide the containers into prefabricated slots. Usually, these are stacked into nine or ten tiers to ensure that there isn’t any risk of them becoming unstable in their bays. Other considerations like weight distribution and the overall design of the ship will also determine how many containers will fit on a specific ship.
Still following? Well, there’s another challenge to accurately defining how many containers fit on a ship. That challenge is that containers come in all different sizes, not just 20-foot variants, so the measurement of TEU can really only tell you the maximum amount of 20-foot shipping containers that can fit on a ship, not the number that really does. Indeed, there are 40 and 45-foot shipping containers that regularly travel on board ships which greatly impacts the overall number that travels at any one time. As you might have anticipated, a 40-foot shipping container is equivalent to two TEUs.
Another limiting factor to the number of containers that can fit on a ship has to do with the ship itself. More specifically, things like the physical dimensions, strength, and draft limitations will have implications for how many containers it can transport. Additionally, stability varies from ship to ship, which makes it difficult to apply a one size fits all answer to the question of how many containers a given ship can carry, even if they share a classification with another container ship. What’s more, each ship will have different loading and unloading functionality which will influence how many containers it can take onboard and perform effectively.
One final point to consider is how quickly the shipping industry is moving in terms of technological innovations. With ever-evolving technology comes the ability to transport a greater number of containers at the same time. With many more revolutions just around the corner, it’s likely that this article will date quickly and there will be capabilities that extend beyond even the mightiest of ULCVs!
Ultimately, the question of how many containers fit on a ship is troublesome at best and requires a little more detail if you want to reach an approximate answer. Whilst it is helpful to know that ULCVs are currently capable of carrying up to 24,000 TEUs, it’s important to note that this is an inexact measurement and the better question to ask is, “What is the greatest number of containers carried by a specific ship?” Whilst this would of course introduce many more challenges, it’s the best way of finding out the answer to your question!
