How Old Is That Container? Reading the CSC Plate & Door Markings

Every shipping container carries its own ID card, if you know where to look. Painted markings and a small metal plate on the doors tell you how old a container is, what it's rated to carry, who owned it and what type it is.

Here's how to read them, so you can judge the age and specs of any of the used ship containers for sale you're considering, from photos or in person.

Where to look

Stand facing the doors. You'll usually find:

• The unit number at the top right of the right-hand door, and on the sides and roof
• The size and type code just below the unit number
• Weight markings (max gross, tare, payload and capacity) on the right-hand door
• The CSC plate and other data plates on the left-hand door

The CSC plate: the container's age

The CSC safety approval plate is a small metal plate, often riveted to the left-hand door. CSC stands for the International Convention for Safe Containers. It shows:

• Date manufactured: month and year. This is the container's age.
• Identification number: the manufacturer's serial number.
• Maximum operating gross mass: the most it can weigh loaded.
• Allowable stacking weight: how much can be stacked on top of it.
• Racking test load: a measure of its strength against twisting.
• Approval reference: which country and authority approved the design.
• Examination information: the date of the next examination or an ACEP reference, which shows whether it's kept in condition for international shipping.

If the plate is missing or unreadable, the container's age is harder to confirm. That matters little for storage, but a container without a valid plate can't go back into international shipping.

The unit number

The unit number is the container's unique ID, and it follows an international standard (ISO 6346). It looks like this:

ABCU 123456 7

• ABC: the owner code, which identifies the company that owns or owned it
• U: the equipment category; "U" means a freight container
• 123456: the serial number
• 7: the check digit, which catches errors when the number is copied

Make sure the unit number on your quote matches the one on the container that arrives.

The size and type code

Below the unit number, you'll see a four-character code such as 22G1 or 45G1:

• First character: length. "2" means 20 feet, "4" means 40 feet, "L" usually means 45 feet.
• Second character: height. "2" is standard (8′ 6″), "5" is high cube (9′ 6″).
• Last two characters: type. "G1" is a general-purpose container; "R1" is a reefer; "U1" is an open top; "P1" or similar is a flat rack.

So 22G1 is a standard 20ft dry container, and 45G1 is a 40ft high cube. It's a quick way to check you're getting the height you paid for.

The weight markings

On the right-hand door, look for:

• MAX GROSS: the most the container and its contents can weigh
• TARE: the empty weight
• NET or PAYLOAD: the most cargo it can carry
• CU. CAP.: the interior volume

These are specific to the unit, so they're more accurate than any general spec sheet.

Other markings you might see

• Yellow and black stripes along the top edge, common on high cubes, warning of the extra height
• Fumigation or treatment labels, usually old placards from previous cargo
• Owner logos, from a shipping line or leasing company
• Repair stencils or dates from past inspections

Using markings to judge a used container

• Age: a younger container usually has more life left, but condition matters more than age.
• Type and height: confirm the code matches what you're paying for.
• Ownership history: a leasing company's logo often means regular inspections; a shipping line's logo means it worked hard at sea.
• Strength: stacking and gross ratings tell you how much it was built to carry.

Asking for markings when buying sight-unseen

Ask for close-up photos of:

1. The unit number and size/type code on the doors
2. The CSC plate
3. The weight markings

Together they tell you the container's age, type and specs before you pay.

FAQ

How do I tell how old a shipping container is?

Look at the CSC plate on the door, which shows the month and year it was made.

What does 45G1 mean on a container?

A 40ft high cube general-purpose container: "4" for 40 feet, "5" for high cube, and "G1" for general purpose.

What if the CSC plate is missing?

You can still use the container for storage, but you can't easily confirm its age, and it can't go back into international shipping without being re-plated.

Can I look up a container's owner from its unit number?

The four-letter owner code is registered with the Bureau International des Containers (BIC), so it usually identifies the company that owns or owned the container. Detailed service history generally isn't public.

Why does the unit number matter?

It uniquely identifies the container. Matching it to your paperwork proves you received the box you paid for.