A UN Number, or United Nations number, is a four-digit code used to identify hazardous substances and articles in transport. It helps shippers, carriers, customs brokers, and emergency responders recognize the specific dangerous goods being moved, regardless of the product name used on paperwork or in trade. The code is assigned to a material or group of similar materials in international dangerous goods classifications.
Why it matters in shipping
The UN Number appears on many shipping documents for regulated cargo, including the dangerous goods declaration, packing instructions, labels, and sometimes the bill of lading or air waybill. It is used together with the proper shipping name, hazard class, and packing group, if applicable, so the cargo can be handled, stowed, and segregated correctly. The exact documentation and marking requirements depend on the mode of transport and the applicable rules, such as ocean, air, or domestic trucking standards.
Using the correct UN Number is important because different products can have different hazards even when they seem similar. For example, one chemical may require a specific number, packaging, and label, while another product in the same general category may not be regulated the same way. If the wrong number is used, a shipment may be delayed, rejected, or misdeclared, which can create compliance and safety problems. In practice, the shipper or its hazardous materials specialist usually confirms the proper classification before booking the freight.