What are shipping container grades?
Container grades are labels sellers use to describe a box’s condition. They are trade terms. No single law or standard defines them, so two sellers can use the same word to mean slightly different things.
The five labels you will see most are one-trip, IICL, cargo worthy, wind and water tight, and as-is. Each tells you something different about structure, weather protection, and price. For a rental fleet, the right grade depends on how the box will be used.
| Grade | Plain meaning | Typical use in a rental fleet |
|---|---|---|
| One-trip | Made one ocean voyage with cargo | Premium rentals, modifications, offices |
| IICL | Used box that met a lessor’s inspection criteria | Core rental fleet |
| Cargo worthy (CW) | Fit for sea transport, passes CSC inspection | Core fleet, boxes that may ship or stack |
| Wind and water tight (WWT) | Keeps weather out, may not stack or ship | Fixed on-site storage |
| As-is | Sold with no promise of condition | Rough storage, parts, or sheds |
Use the table as a start. Then ask each seller for its own definition in writing.
What is a one-trip container?
A one-trip container has made a single ocean voyage with cargo. After that trip, sellers market it as near new. See the glossary entry on one-trip containers.
Boxhub describes one-trip units as having been used once to ship a single load of dry cargo to the U.S. It says they are built to last 25 to 30 years and remain cargo worthy if recertified. Boxhub also offers a five-year condition guarantee on them. That guarantee is the seller’s own promise, not an industry rule.
Check three things on any one-trip box:
- The date of manufacture and the CSC plate.
- Dents, scrapes, and door-seal wear from that one trip.
- The floor and its treatment. Ask what was applied.
New boxes cost more. One supplier listed a new 20 ft box at $2,755 against $1,975 for a used one in October 2026. Prices vary by region and change often. For floor treatment questions, read the NPSA blog post on floor treatment safety.
What does IICL mean?
IICL stands for the Institute of International Container Lessors. It is the trade association of the marine container leasing and chassis provider industry. See IICL in the glossary.
According to IICL’s own site, it publishes manuals and tools, technical documents, ISO and CEDEX codes, and training and certification for container and chassis inspectors. The page says it is “active in developing standards.” It also says member equipment quality depends on the skills and knowledge of inspectors.
An “IICL container” is a used box that has passed inspection criteria set by the lessors’ group. Boxhub says it is usually only used by marine container leasing companies. It describes IICL boxes as guaranteed wind and water tight, with solid flooring and no structural issues. Boxhub gives a four-year guarantee on them.
For a buyer, the practical point is simple. IICL is a reference to a lessor’s criteria, not a government approval. Ask the seller which criteria and which edition they used. Ask for the inspection record.
What does cargo worthy mean?
Cargo worthy (CW) means a box can pass a CSC inspection and carry cargo at sea. It is structurally sound, weathertight, and suitable for shipping. See cargo worthy in the glossary.
Boxhub says cargo-worthy containers may show slight wear and tear on the inside and outside. Cosmetic dents and rust do not make a box unfit for cargo. The test is structure, not paint.
Conexwest, a U.S. supplier, sells three grades: new one-trip, used cargo worthy, and refurbished cargo worthy. It describes used cargo worthy as certified for global transport on doors, floor, walls, and ceiling, with dents, rust, or weathered paint possible. It says refurbished units meet the same standard after sanding, rust removal, primer, and new paint. It also says it does not sell as-is or WWT boxes. That is one company’s policy, and other sellers choose differently.
A third-party surveyor can verify condition. See container survey and container condition report.
What does wind and water tight (WWT) mean?
Wind and water tight (WWT) means the box keeps weather out. The roof, walls, and doors should not let in rain or wind, and the floor should be intact. See wind and water tight in the glossary.
Boxhub says WWT boxes are guaranteed watertight, with intact floors and doors that seal. It adds that they no longer meet the structural requirements for stacking, so they cannot be used for shipping. It says these boxes typically spent 15 to 20 years at sea.
A common field test is the light-leak test. Someone stands inside the closed box and looks for daylight through the walls, roof, and door gaskets. That test checks the shell. It does not check the underframe or corner posts. A WWT label is not proof of structural strength.
For many fixed rental sites, WWT is enough. A box that sits on a customer’s driveway and never ships does not need to be cargo worthy. It does need to stay dry and secure.
What does as-is mean?
As-is means the seller makes no promise about condition. Boxhub says as-is containers may have broken floors, holes, and extensive rust, and structural integrity is not guaranteed.
Boxhub suggests them for temporary storage of hardy materials or for garden and barn sheds. They are the lowest-cost grade. For a rental fleet, an as-is box carries real risk: a leak can damage a customer’s goods and lead to a claim. Inspect every as-is box in person before you buy, and consider whether the savings justify the risk.
What is a CSC plate, and how does it relate to grade?
A CSC plate is a safety approval plate required on containers that travel internationally. It comes from the 1972 International Convention for Safe Containers. Wikipedia’s article on intermodal containers says the convention requires every container traveling internationally to carry the plate, which records information such as age, dimensions, weights, and stacking capability. See CSC plate and Convention for Safe Containers.
The plate is not a grade. It does not say one-trip, WWT, or IICL. It shows approval and an examination schedule.
According to the TT Club, new containers need no formal examination for their first five years. After that, a box must be examined at least every 30 months. Owners may use either of two schemes:
| Scheme | How it works |
|---|---|
| Periodic examination | The owner tracks each box’s due date and arranges an exam. The box gets a next-exam date no more than 30 months out. |
| Continuous examination (ACEP) | The owner runs an approved process with set pass and fail criteria and exam triggers. |
See periodic examination scheme and ACEP. Whether a box that never ships needs a current exam depends on how it is used and which rules apply. Ask your surveyor or attorney. A box sold for cargo use should have a valid plate.
Standards also set dimensions and test methods. ISO 668 covers sizes and ratings. ISO 1496-1 covers testing of general-purpose containers. For sizes, read container sizes and dimensions.
How do I choose the right grade for a rental fleet?
Match the grade to the job and the risk. Use this checklist when you buy:
- Define the use: fixed storage, stacking, shipping, or modifications.
- Ask the seller to define each grade term in writing.
- Get photos of the inside, the roof, the floor, the doors, and the corner posts.
- Ask for the CSC plate date and any survey or inspection report.
- Test for light leaks and door function.
- Compare the warranty terms, not just the label.
Seller warranties vary. Boxhub offers five years on one-trip and four years on IICL boxes. Conexwest lists 10 years on new ISO boxes and five years on used cargo-worthy ISO boxes. Those are separate company offers. Read the exclusions. Conexwest, for example, excludes surface corrosion and cosmetic wear.
Price differences are real but vary by region. For buying advice, read the guide on buying containers wholesale. For modifications that can affect structure, see container modifications.
What should I ask a seller to put in writing?
Ask for the seller’s own definitions, because the labels are not standardized. A good seller answers these questions without delay:
- What does your term mean? For example, does cargo worthy mean a current CSC exam, or only that the box could pass one?
- What is the date of manufacture, and what does the CSC plate show?
- Is there a survey, an inspection report, or photos from the day of sale?
- What does the warranty cover, for how long, and what is excluded?
- Does the price include delivery to your yard, and how is the box delivered?
- Can I inspect the box, or send a surveyor, before I pay?
Keep the answers with your purchase record. If a customer claims a leak later, you will know what you bought. Do not rely on the label alone. A seller who shrugs at these questions is a risk.
Do rental operators need cargo-worthy boxes?
Not always. Many rental boxes stay on a customer’s lot and never go to sea. For those, weather protection, working doors, and a sound floor matter most. A WWT box can meet that need at a lower price.
Cargo-worthy or one-trip boxes make sense when you plan to modify the box, ship it, stack it, or sell it to a buyer who may ship it. They also help when your brand depends on a clean look. Decide by use, not by habit. Many fleets mix grades and track each box by serial number so they know which box went where.
What should I tell customers about grade?
Keep it simple. Customers care about three things: will it leak, is it secure, and does it look acceptable. Most do not need grade names.
Your fleet standard matters more than a label. Inspect every box between rentals. Fix leaks and door problems before delivery. Record each box’s condition with photos. See container inspection for the idea.
Next step
Want to compare notes with other operators and meet container suppliers face to face? See the NPSA events page.