Shipping containers are sold by grade — a short description of condition, remaining service life and what the unit is fit to do. Grade is the single most important word on any container listing, because it explains why two identical-looking 40ft boxes can differ by $3,000. This guide defines every grade you will encounter, what to expect physically from each, and which one to buy for your job.
A word of warning that applies across the whole industry: grade terminology is conventional, not legally defined. “Cargo-worthy” has a real technical meaning tied to survey and certification; “A-grade” and “premium” do not. Buy on the described condition and the photographs, not on an adjective.
The Grade Comparison Table
| Grade | Typical age | Condition | Best for | Watch for |
|---|---|---|---|---|
| One-trip / new | 1–2 years | Factory paint, clean floor, new gaskets | Conversions, retail, anything visible | Minor transit scuffs |
| Multi-trip | 2–5 years | Light wear, sound paint | Near-new appearance at lower cost | Isolated dents |
| Cargo-worthy (CW) | ~8–15 years | Surface rust, dents, solid structure | Storage, jobsites, general use | CSC plate date; floor condition |
| Wind & watertight (WWT) | 10+ years | Sealed and dry, more cosmetic wear | Static dry storage | Door seals; roof ponding |
| Refurbished | Varies | Repaired and repainted | Appearance on a budget | What was repaired, and how |
| As-is / storage class | 12+ years | Sold in stated condition | Cheap steel, project boxes | Everything — read the listing |
One-Trip (New)
Manufactured recently and shipped once with cargo before being sold into this market. The closest thing to a factory-fresh container that exists domestically. Paint is intact and uniform, the plywood floor is unmarked, the door gaskets have never perished and the cam-and-rod gear operates without persuasion.
Buy one-trip when the container will be modified, painted, or seen by customers, or when you want the maximum remaining service life. See the one-trip stock for what is currently available across sizes.
Cargo-Worthy (CW)
Cargo-worthy is the only grade with a technical basis behind it. A cargo-worthy container has been surveyed and found structurally sound and fit for international carriage; where a unit carries a current CSC plate, we state that on the listing.
The CSC plate matters more than most buyers realize. Under the International Convention for Safe Containers, a container in cargo service must undergo its first examination before the fifth anniversary of manufacture and be re-examined at intervals not exceeding 30 months thereafter, with the next examination date marked on the plate. The plate itself is required to be at least 200 mm by 100 mm, permanent, non-corrosive and fireproof, and to carry the month and year of manufacture, the maximum payload in both kilograms and pounds, and the stacking and racking test values.
Practically, that means the CSC plate is a dated, verifiable record of the container's age and inspection history — the one piece of documentation on the box that is not marketing. If you plan to ship, stack or resell the unit, buy cargo-worthy and check the plate. A cargo-worthy 40ft standard is the volume seller in this grade.
Expect: surface rust in patches, dents on the side panels and roof, faded and patched paint, a floor that has taken forklift traffic but supports it, and doors that seal. Do not expect: perforations, structural corrosion, or a floor with soft spots.
Wind & Watertight (WWT)
A WWT unit keeps weather out and stays dry inside, but is not being sold as certified for ocean carriage. Usually it is a container that has aged past what a surveyor will certify, or one whose CSC examination has lapsed, while remaining perfectly serviceable as a static box.
This is the value sweet spot for pure storage. You are paying for the function you actually need — a sealed steel room — and not for a certification you will never use. A 40ft wind-and-watertight unit typically costs several hundred dollars less than the cargo-worthy equivalent.
Two things to check on any WWT unit: the door gaskets, which are the most common leak path and cheap to replace; and the roof, where a dent that ponds water will eventually corrode through from the top.
Refurbished
A used container that has been repaired and repainted before sale — damaged panels straightened or replaced, corrosion cut out and welded, and the whole unit coated. A well-executed refurbishment gives close to one-trip appearance for meaningfully less money.
The question worth asking is what was repaired. Paint hides history, and a repaint over sound steel is a very different product from a repaint over a patched corner post. Ask, and expect a straight answer.
As-Is / Storage Class
Sold in the condition described, with no representation beyond that description. This is the cheapest steel per square foot in the market and it is entirely legitimate — provided you read the listing and know what you are taking on. Typical issues include perished door seals, dents that pond water, rust perforations, and floors needing patching.
As-is suits buyers who can weld, or who need a container for a purpose where a hole in the roof is irrelevant. It does not suit anyone who needs the contents dry on day one. If in doubt, spend the extra few hundred dollars and buy wind-and-watertight instead.
What Grade Does Not Tell You
Grade describes the shell. It says nothing about:
- Door configuration. Standard end doors, double door (doors at both ends), side-opening or roll-up shutter are all separate specifications. A 20ft double door container is a different product from a standard 20ft at the same grade.
- Height. Standard versus high cube is a dimension, not a grade.
- Previous cargo. Worth asking about if you are storing anything sensitive to odour or residue.
- Floor treatment. Container plywood is typically treated against insects and decay as a condition of international movement.
- Modifications. Vents, lock boxes, shelving and lining are options, not grades.
Matching Grade to Job
| Application | Grade to buy | Why |
|---|---|---|
| Backyard or garden storage | WWT or cargo-worthy | Dry inside; appearance rarely critical |
| Farm equipment and feed | Cargo-worthy | Robust, watertight, priced sensibly |
| Jobsite tool storage | Cargo-worthy or WWT | Working environment; security matters more than paint |
| Office or workshop conversion | One-trip | Clean base for cutting, lining and painting |
| Retail, bar or customer-facing | One-trip or refurbished | Finish is part of the product |
| Shipping cargo internationally | Cargo-worthy with current CSC plate | Certification is a hard requirement |
| Project box you will rebuild | As-is | Lowest entry cost; you are buying steel |
How to Verify the Grade You Were Sold
- Read the CSC plate. Month and year of manufacture, maximum gross weight, and the next examination date if the unit is still in the periodic scheme.
- Close the doors and look for daylight. The single fastest watertightness test there is.
- Walk the floor. Flex, soft spots or delamination mean deferred cost.
- Check the bottom rails and corner posts. Surface rust is fine; scale you can push a screwdriver through is not.
- Look along the roof from a height. Dents that hold water are the most commonly missed defect.
The full walkthrough is in our container inspection guide, and the standard shipping containers category is a good place to compare grades side by side at the same size. If you want the price implications spelled out, the container price guide shows the spread by grade.
We list the grade on every unit in the containers-for-sale listings, and each unit is inspected before dispatch. If the grade on arrival does not match the listing, tell us — that is a problem we want to fix, and it is covered by the 30-day return window.
Frequently Asked Questions
What does cargo-worthy mean?
A cargo-worthy container has been surveyed and found structurally sound and fit for international carriage. Where a current CSC plate is fitted, the container remains within the periodic examination scheme required for cargo service. Cosmetic wear such as surface rust and dents is normal and does not affect the grading.
What is the difference between cargo-worthy and wind and watertight?
Cargo-worthy is about certification for ocean carriage as well as condition; wind and watertight is only about keeping weather out. A WWT unit is dry and sealed but is not offered as certified for shipping, which is why it usually costs several hundred dollars less than the cargo-worthy equivalent of the same size.
How do I check a container's age?
Read the CSC plate. It is required to carry the month and year of manufacture, along with the maximum gross weight and the stacking and racking test values. Containers still in the periodic examination scheme also show a next examination date, which must fall within 30 months of the previous examination.
Is an as-is container worth buying?
It depends entirely on your ability to assess and repair it. As-is is the cheapest steel available and legitimate stock, but it is sold on the description alone and may need floor patching, seal replacement or welding. If you need the contents dry from day one, buy wind and watertight instead.
Which grade should I buy for a container conversion?
One-trip, in nearly all cases. Cutting windows and doors into corroded steel means welding back to sound metal, more preparation and a poorer finish. Since a conversion costs far more than the donor box, starting from the cleanest available shell is the cheaper decision over the life of the build.