ISO 6346 Container Number Structure Explained

Four parts

A container number has 11 characters: a three-letter owner code, a one-letter equipment category identifier, a six-digit serial number, and a check digit.

Extracting It Automatically

When you read this data from photos, the Container Number OCR API returns it as structured JSON, and you can apply the rules on this page as validation. Try it with the free scanner.

Where This Fits

• Equipment category: U marks freight containers, J detachable freight-container equipment, and Z trailers and chassis.
• Owner codes: Owner codes are registered with the Bureau International des Containers (BIC), which is why the combined prefix is often called a BIC code.
• Markings: Numbers appear on doors, sides, and roofs, sometimes vertically. The size and type code is printed nearby.

Extract It with the API

Read the document from a photo and validate the returned fields.

Prerequisite: Python 3.9+, `pip install requests`, and a STRUCTOCR_API_KEY

import base64
import os
import requests

with open("container.jpg", "rb") as image_file:
    image = base64.b64encode(image_file.read()).decode("ascii")

response = requests.post(
    "https://api.structocr.com/v1/container",
    headers={"x-api-key": os.environ["STRUCTOCR_API_KEY"]},
    json={"img": image},
    timeout=30,
)
response.raise_for_status()
data = response.json()["data"]
print("container_number:", data.get("container_number"))
print("is_valid:", data.get("is_valid"))
print("confidence:", data.get("confidence"))

Reference Summary

Key facts from this page in structured form, for quick lookup.

{
  "Four parts": "A container number has 11 characters: a three-letter owner code, a one-letter equipment category identifier, a six-digit serial number, and a check digit..",
  "Equipment category": "U marks freight containers, J detachable freight-container equipment, and Z trailers and chassis..",
  "Owner codes": "Owner codes are registered with the Bureau International des Containers (BIC), which is why the combined prefix is often called a BIC code..",
  "Markings": "Numbers appear on doors, sides, and roofs, sometimes vertically."
}