What Is a UN Identification Number?

UN Identification Number A four-digit United Nations identification number assigned to a hazardous material or dangerous good for transport purposes.

First used and referenced on shipping papers, labels, and emergency response guides, the UN Identification Number is the single, four-digit numeric code that identifies a specific hazardous substance or a generic class of dangerous goods for transport. It appears in international and national dangerous-goods regulations (for example in the IMDG Code for sea, the ICAO Technical Instructions for air, and the United Nations Model Regulations) and is the standardized shorthand used by carriers, emergency responders, and regulators worldwide.

How The Number Is Structured And Applied

Each code is four digits (for example, UN1203 for gasoline or UN1993 for flammable liquid, n.o.s.). The digits themselves do not carry hierarchical meaning like a prefix or suffix — the value maps to an entry in the UN Dangerous Goods List, which supplies the proper shipping name, hazard class/division, packing group (where applicable), and handling requirements. The designation is commonly written on documentation and markings as "UN" followed immediately by the four digits.

Why It Matters For Shippers And Carriers

Using the correct UN Identification Number determines the packaging, labeling, placarding, segregation, and documentation required for a consignment. Emergency responders use the UN number to look up the material in guides such as the Emergency Response Guidebook (ERG) and determine immediate action for spills, fires, or exposures. Incorrect or missing UN numbers can delay shipments, trigger enforcement action, or produce unsafe handling in an incident.

When And Where You Must Use It

Regulatory systems require the UN number in many places:

• Shipping Papers: The UN number and proper shipping name are mandatory entries on air waybills, dangerous goods declarations, bills of lading and other transport documents.
• Marking and Labeling: Packages and outer packaging commonly carry the UN number near the orientation arrows or within a diamond label, per modal rules.
• Placarding: Road and rail consignments meeting quantity thresholds must display the UN number on placards.

How The Number Is Assigned And Updated

UN numbers are assigned through the United Nations' process for the transport of dangerous goods. The UN Committee of Experts compiles and maintains the Model Regulations and Dangerous Goods List. When chemical producers, national authorities, or industry groups propose a new entry, the committee evaluates hazards, transport behavior, and compatibility before assigning a number or updating an existing entry. National administrations then adopt or adapt the UN list into domestic regulations (for instance the U.S. Hazardous Materials Regulations implements the UN-based approach for most goods transported in the United States).

How It Differs From Similar Identifiers

Several other codes exist that can be confused with UN numbers:

• NA Numbers: Used in the United States for some materials; they are North American identifiers that may correspond to the same substance but are applied domestically.
• UN Proper Shipping Name vs. Technical Name: The UN number ties to the proper shipping name; a chemical’s technical or trade name may differ and should not replace the UN designation on transport documents.
• CAS Numbers: Chemical Abstracts Service numbers identify chemical substances for scientific referencing but are not used for transport classification.

Practical Example — How A Shipper Uses A UN Number

A merchant preparing a pallet of lacquer thinner will identify the product’s UN number (for example UN1993 if it is a flammable liquid, n.o.s., and that entry applies). They will then select certified packaging rated for the packing group, add the correct hazard labels, complete the dangerous goods declaration with the UN number and proper shipping name, and ensure the carrier accepts the commodity for the intended mode (air, sea, road). Emergency contact and ERG references tied to the UN number are included on transport paperwork.

Tips For Warehouse And Logistics Teams

• Label Check: Verify the UN number on the manufacturer’s SDS (safety data sheet) and cross-check with the UN Dangerous Goods List before shipping.
• Mode-Specific Rules: Confirm special provisions in the IMDG Code or ICAO Technical Instructions — the same UN number can carry different restrictions depending on the transport mode.
• Training: Ensure staff who prepare shipments and those who load vehicles are trained in dangerous goods regulations and in locating the UN number on documentation and labels.

In short, the UN Identification Number is the universal four-digit code used to identify hazardous materials for transport. Correct use of the number speeds regulatory compliance, informs packaging and placarding decisions, and provides first responders with the information they need to protect people and property.