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UN-Number and Dangerous Goods Classes: How are they related?

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What actually is a dangerous goods class and what does it say about the dangerous goods? And what role does the UN-Number play in the classification of dangerous goods?

The so-called UN-Numbers, together with the dangerous goods classes, form the two basic features of how dangerous goods are categorized uniquely and across languages. In this blog post, we would like to explain what UN-Numbers are as well as give you an overview of the dangerous goods classes. We will also explain how you can recognize the correct classification.

The UN-Number for Dangerous Goods: Four Digits, clear Statement – Worldwide

The UN number is a number that always consists of four digits and is preceded by “UN“. It is also called substance number.

The special feature: Each hazardous substance or item is assigned exactly such a UN-Number. This means that the substance or item can be clearly identified via this number, including important information about the hazards that potentially emanate from it.

In addition, there is a list in the dangerous goods regulations in which all UN numbers are sorted. This then also lists specifications about the type of packaging, necessary labeling, any exemptions and special regulations. Information on the limited quantity can also be found in this list.

UN-Number and Dangerous Goods Classes: How are they related? | ProSafeCon
Information from the substance list using the example of UN-Number 1203, gasoline

Since this categorization is based on numbers, this assignment is independent of the language of the country in which the transport is currently located! This makes this assignment understandable worldwide – and in the event of an incident or accident, it helps police and rescue forces universally to provide targeted assistance and contain damage to people, animals and the environment.

Where can I find the UN-Number for Dangerous Goods on my Product?

Whether a product, substance or object has a UN-Number can partly be taken directly from the label on the packaging.

However, you can find this information completely unambiguously and reliably on the safety data sheet, which should be available to you. Here the UN number can be found under section 14.

You do not have a safety data sheet – or in the case of batteries a test summary? Then it is best to contact the manufacturer, or your supplier – both must be able to provide this information.

By the way, a simple rule: If a product, substance or object has a UN-Number, it is dangerous goods! In this case, it is necessary to check which regulations apply and there are various obligations that apply to those involved in the dangerous goods process. You can find out more about the obligations here.

You are unsure which regulations have to be observed for your transport? Contact us! We will be happy to help you.

Overview of the dangerous goods classes

In contrast to the UN numbers, where each substance or object is assigned exactly one number, the dangerous goods classes are more or less collective groups. Decisive for the classification in the dangerous goods class are, among other things, the aggregate state of the substance (solid, liquid, gaseous) and which special features give the substance the dangerous potential.

There are 9 different superordinate dangerous goods classes into which dangerous goods can be divided. In addition, there are subclasses and special classes such as “environmentally hazardous substances”:

UN-Number and Dangerous Goods Classes: How are they related? | ProSafeCon
Overview of the dangerous goods labels ( German labeling)

Gefahrgutklassen im Überblick

  • Class 1 – Explosive substances
  • Class 2 – Gases and gaseous substances
  • Class 3 – Flammable liquids
  • Class 4.1 – Flammable solids, self-reactive substances, desensitized explosives
  • Class 4.2 – Substances liable to spontaneous combustion
  • Class 4.3 – Substances which form flammable gases with water
  • Class 5.1 – Flammable substances
  • Class 5.2 – Organic peroxides
  • Class 6.1 – Toxic substances
  • Class 6.2 – Infectious substances
  • Class 7 – Radioactive substances
  • Class 8 – Corrosive substances
  • Class 9 – Miscellaneous dangerous substances and articles

Other markings:

  • Environmentally hazardous substances
  • Marking for materials transported in a heated state

Although the UN number is much more precise, the class of dangerous goods makes it possible to identify the danger more quickly and more strikingly.

Hazardous Goods Classes: Clear Labeling for Hazard Groups

The labeling of dangerous goods is done with the so-called “danger label”, for which the dangerous goods class and the safety sign (pictogram) play a role.

UN-Number and Dangerous Goods Classes: How are they related? | ProSafeCon

Especially when transporting hazardous liquids by tank, there is also the hazard board. This shows the hazard number (two digits) and the UN number (four digits). It is known above all from fuel transports: The hazard table for gasoline consists of the number 33 and the subordinate UN number 1203.

UN-Number and Dangerous Goods Classes: How are they related? | ProSafeCon

The signs of the dangerous goods class are in most cases clearly understandable even for laymen. Thus, the dangerous goods of the different classes can be clearly assigned to one of the warning signs. For example, the fact that a flame is a flammable substance and the explosion symbol is an explosive substance can be understood even without specialist knowledge.

Just like the UN-Number, these markings are also standardized worldwide. This means that even when transporting goods in other countries, it is possible to recognize at first glance the potential danger posed by the respective package.


  1. The UN-Number is also called substance number and consists of four digits. It is uniquely assigned.
  2. In the dangerous goods regulations there are lists in which all UN numbers are listed. Here you can read important information about danger, packaging regulations and markings.
  3. The UN number can always be found in the safety data sheet.
  4. Dangerous goods classes are groups to which dangerous substances or objects are assigned, primarily on the basis of their aggregate state and main hazard.
  5. Based on the labeling on packaging or transports, hazards can be quickly identified with the help of the dangerous goods classes.




You would like to read more about a topic here? Contact us! We are looking forward to your topic requests. As an external dangerous goods safety advisor, we are on the road for you throughout Germany.

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UN-Number and Dangerous Goods Classes: How are they related? | ProSafeCon

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