ISO Container Condition Grades Explained

A practical guide to container grades for businesses and buyers

All used shipping containers look similar from 10 feet away. The condition grade is what tells you what you’re actually buying — how much life it has left, what it can be used for, and what you should pay. Use this guide to decode the grades.

1. The ISO Grading System at a Glance

There is no single global law for grading, but the industry uses these 5 standard grades everywhere:

Grade	Also Called	Age	What It Means
One-Trip / New	Like-New, Single-Use	< 1 year	Shipped cargo once, then sold. Minimal wear.
IICL-5	Premium Used	5-8 years	Meets strict IICL repair standard. Best used grade.
Cargo Worthy (CW)	Certified for Shipping	8-15 years	Passes inspection, safe to ship cargo internationally.
Wind & Watertight (WWT)	Storage Grade	10-20 years	No leaks, no holes, doors close. Not certified for shipping.
As-Is / Damaged	Needs Repair	Any	Sold with visible damage, rust, or faulty doors. Cheapest.

2. Detailed Breakdown

1. One-Trip / New Condition

Built in the last 12 months, loaded once from factory to destination.
May have small dents, light surface rust on hinges, and shipping stickers.
Inside is spotless, floor is perfect, door seals are new.
Best for: Conversions into offices, homes, shops, kiosks — anything where appearance matters. Also best for long-term storage.
Cost: Highest, but you get 25+ years of life.

2. IICL-5 Grade

IICL is the Institute of International Container Lessors — their repair standard is the strictest in the world.
Containers must pass a 200+ point check. Any dent over a certain size, any rust patch, any door issue must be repaired to near-factory spec.
Best for: Buyers who want a used price with near-new reliability. Great for export businesses.
How to verify: Ask for IICL-5 certificate.

3. Cargo Worthy (CW)

Inspected by a licensed surveyor and certified to still ship cargo.
Must be structurally sound, doors must seal, floors must hold weight, no daylight visible when closed.
Will have dents, surface rust, patches, and faded paint — that’s normal.
Best for: International shipping, heavy storage, businesses that need certification for insurance or port use.
How to verify: Ask for valid CW certificate, usually valid for 12 months.

4. Wind & Watertight (WWT)

The workhorse grade. This is what 70% of buyers choose for storage.
Guarantee: No holes, no leaks, doors open and close, floors are solid.
Not certified for shipping cargo overseas.
Will show age — dents, rust, repairs, older paint.
Best for: Ground-level storage, workshops, equipment storage, budget conversions where you will repaint or clad anyway.
What to check: Open the doors on a sunny day and close yourself inside. If you see daylight, it’s not truly WWT.

5. As-Is / Damaged

Sold exactly as found. May have holes, heavy rust, broken door handles, damaged floors, or off-track doors.
Cheapest, but you pay for repairs.
Best for: Scrap projects, spare parts, or buyers with welding skills who want to do the restoration themselves.
Avoid this grade if you need immediate storage.

3. Which Grade Should You Buy?

Ask yourself 3 questions:

Will it ship internationally? → You need Cargo Worthy or better.
Will customers see it? (Office, cafe, home, retail) → Choose One-Trip or IICL-5.
Is it just for secure storage on your property? → WWT gives you the best value.

Quick Decision Guide:

Maximum lifespan + best appearance: One-Trip
Best quality used container: IICL-5
Need to export or need a surveyor certificate: Cargo Worthy
Best value for storage: Wind & Watertight
Cheapest + DIY repair: As-Is

4. Red Flags When Buying Any Grade

No matter the grade, reject a container if:

You can see daylight through roof or panels when doors are closed
Floor is soft, delaminated, or smells strongly of chemicals
Door locking bars are bent or handles won’t lock with moderate force
Heavy flaking rust that you can poke a hole through
No CSC plate (the metal safety plate on the door) — this indicates it may not be ISO compliant

Bottom Line

Don’t buy on price alone — buy on grade for your use case. For most businesses, a certified WWT container is the sweet spot for storage, while a One-Trip container is worth the extra cost for any conversion where image and longevity matter.

Pro Tip: Always ask for dated photos of the exact container — not stock photos — showing the interior, doors open and closed, floor, roof, and CSC plate. A trustworthy supplier will provide them before payment.