How to Read Container Markings and the CSC Plate.

Walk up to any container in our yard and the doors are covered in codes, numbers, and a metal plate riveted to the left-hand door. None of it is decoration. A container wears its identity and its rated capacity right on its skin, and a buyer who can read it walks in knowing more than most sellers expect.

Here's the five-minute version.

The container number

The big one, painted top-right on the doors and repeated on the sides: four letters followed by seven digits, something in the shape of ABCU 123456 7.

• First three letters: the owner or operator code, registered to whichever shipping line or leasing company originally ran the box.
• Fourth letter: almost always U, meaning a freight container.
• Six digits: the serial number.
• Last digit, boxed: a check digit, calculated from everything before it. It exists so a typo in paperwork gets caught by math.

This number is the container's identity for life. When you buy from us, it's how you confirm the box that lands in your driveway is the box in the photos you approved. Match it. Takes ten seconds.

The size and type code

Under the container number sits a shorter four-character code, like 22G1 or 45G1. First character is length, second is height, and the last two describe the type. The pattern worth memorizing: 22G1 is a standard-height 20-foot general purpose box, 42G1 a standard 40, 45G1 a 40-foot high-cube. So a glance tells you whether that "high-cube" in an online listing actually is one. Cross-check against our dimensions page if a listing and its code disagree, and trust the code.

The weight panel

On the right-hand door you'll find MAX GROSS, TARE, and PAYLOAD (sometimes NET), each in kilograms and pounds. Max gross is the loaded ceiling the box was rated for in shipping service, tare is the empty weight of the container itself, and payload is the difference: what it may carry.

For a storage buyer, tare is the number you'll actually use. It's what your delivery driver is hauling and what a crane or heavy forklift needs to know if you ever relocate the box. Payload matters if you're loading dense material like tile, paper, or steel stock, which hits weight limits long before the walls fill up.

The CSC plate

The riveted metal plate low on the left door is the CSC safety approval plate, the container's passport under the international Convention for Safe Containers. It carries the manufacture date, the manufacturer, the approval number, and the stacking and racking ratings.

Two things make it useful to you as a buyer. First, the manufacture date is the honest odometer: a seller can repaint a 2005 box, but the plate still says 2005. Second, an ACEP notation or a re-inspection sticker tells you the box stayed in a certified inspection program during its shipping career.

One caution in the other direction: a valid plate is not a condition report. CSC certification is about shipping service, and a box can leave the fleet and rust for years with its plate intact. Condition is what grades are for, and we explain those in our grade comparison and on the grades page.

What the markings can't tell you

Markings give you identity, dimensions, ratings, and age. They say nothing about the door gaskets, the floor, or that dent in the roof holding rainwater. So read the doors, then do the walkaround: our inspection checklist covers the physical side, and photos of the actual unit cover the rest when you're buying remotely.

Every listing in our used inventory is a real, numbered box, and we're happy to read a plate over the phone with you at (302) 579-5617 before you commit to anything.

Disclosure: XIVstorage sells the shipping containers discussed in this article. Typical figures are planning guidance; the product page and unit plate control exact specifications.