The Ultimate Guide to Shipping Container Grades & Conditions
If you are buying a shipping container for the first time, you will quickly notice that they aren't priced just by size—they are priced by grade. Because shipping containers spend their lives crossing oceans, battling salt water, and being stacked at ports, the industry uses a strict grading system to classify their structural integrity and condition. Understanding the difference between a "One-Trip" container and a "Wind & Watertight" container is the most important step in ensuring you don't overpay—or worse, end up with a leaky box that damages your property.
Here is exactly what you need to know about the three main shipping container grades, and which one is right for your specific project.
New / "One-Trip" Shipping Containers
The Premium Option
A One-Trip shipping container is the highest quality container available in the US market, having made only a single cargo trip from its manufacturer in Asia before being sold.
Despite the name, there is no such thing as a truly "brand new" shipping container in the US. Because 99% of shipping containers are manufactured in Asia, they must make one single trip across the ocean carrying cargo to offset the cost of freight. Once they arrive in the United States, they are unloaded and sold.
-
Condition: Excellent. They are essentially brand new. You can expect fresh factory paint, pristine floors, and doors that open and close with zero resistance. They may have a few very minor scuffs or dings from being loaded onto the ship, but there will be no structural damage or rust.
-
Best Used For: Container homes, tiny homes, retail pop-up shops, mobile offices, or residential storage where curb appeal and aesthetics are highly important.
-
The Verdict: If you are modifying the container with windows and doors, or placing it in a highly visible area on your property, a One-Trip container is worth the investment.
Cargo Worthy (CW) Shipping Containers
The Heavy-Duty Option
A Cargo Worthy (CW) shipping container is a used container that has passed a strict marine surveyor inspection and is structurally certified for international ocean freight.
A CW container has spent several years working in the global shipping fleet. To achieve a CW grade, the container must pass a strict structural inspection by a certified marine surveyor. If it passes, it is issued a CSC (Container Safety Convention) plate, meaning it is legally certified to be stacked heavily and shipped overseas.
Condition: Structurally flawless, but cosmetically imperfect. While you can still expect some faded paint, company decals, and minor dents, a CW container will generally be in noticeably better condition with far less severe rust than a standard WWT unit. The floors are intact, the doors seal tightly, and there are absolutely no holes or leaks.
Best Used For: Exporting goods overseas, heavy-duty modification projects, or buyers who want long-term "peace of mind" storage without needing to do immediate rust maintenance.
The Verdict: While CW is legally required if you are shipping internationally, we highly recommend it for everyday storage customers who want a higher quality used unit than WWT. If you don't want to spend time or money grinding away rust to prevent future leaks, paying the slight premium for a CW container is a smart, hassle-free investment.
Wind & Watertight (WWT) Shipping Containers
The Popular Storage Option
A Wind & Watertight (WWT) shipping container is a retired ocean container that is guaranteed to have no holes or leaks, making it the most affordable and popular choice for dry on-site storage.
The WWT grade is the undisputed king of the used container market. These containers have been retired from the active shipping fleet (usually after 10-15 years of service) and are no longer certified for ocean freight. However, they are guaranteed to be entirely weatherproof.​
Condition: Because they are older, WWT containers typically present noticeably more surface rust, dents, and patched repairs than a CW container. The key guarantee of a WWT container is that upon delivery, there are zero holes and your contents will remain 100% dry.
However, because it is difficult to know exactly how deep the existing rust goes, how long they stay watertight untouched can be unpredictable.
Expert Maintenance Tip: To make a WWT container last a very long time, we highly recommend doing a quick inspection upon delivery. Taking a wire wheel to heavy rust spots and applying a fresh coat of rust-inhibiting paint will stop deterioration in its tracks and drastically extend the lifespan of the unit.
Best Used For: General residential storage, farm feed protection, landscaping equipment, and secure job site tool storage.
The Verdict: WWT is the most cost-effective solution for on-site storage. If you do not care about cosmetic scratches and simply need an impenetrable, dry steel box to protect your assets, WWT is the smartest financial choice.
A Warning on "As-Is" Containers
While shopping, you may see heavily discounted containers listed as "As-Is." At US Conex, we strongly advise against purchasing these.
"As-Is" containers have failed their watertight inspections. They often have severe structural damage, holes in the roof, rotted plywood flooring, or doors that are completely seized shut. Trying to patch and repair an As-Is container will almost always cost you more time and money than simply upgrading to a guaranteed WWT unit.
Quick Comparison Summary
Ready to find the right container for your location? Check out our local delivery pages to see live pricing for One-Trip, CW, and WWT containers in your exact area!
About the Author
Laurence, Container Sales Expert: With over 4 years of hands-on experience selling, shipping containers across the US, I help buyers navigate the complex world of container grading and site prep. My goal is to ensure you never overpay for a container and get exactly the right grade for your project.