UN number
A UN number is the four-digit identifier the United Nations assigns to a specific hazardous substance or article for transport — UN1203 for gasoline, UN3480 for lithium-ion batteries. It identifies what the material is, not how dangerous it is: the separate hazard class and packing group carry that information. It is required on shipping documents, placards, and the Safety Data Sheet for any product classified as dangerous goods, and it is the field that determines which transport regulations (49 CFR, IMDG, IATA) apply to a shipment.
What a UN number identifies
A UN number is a four-digit code the UN Committee of Experts on the Transport of Dangerous Goods assigns to a specific hazardous substance, mixture, or article moving through international commerce. It's listed with the prefix "UN" — UN1203 for gasoline, UN1830 for sulfuric acid, UN3480 for lithium-ion batteries — and published in the UN Model Regulations' Dangerous Goods List, which national and modal regulations (the U.S. Hazardous Materials Table in 49 CFR 172.101, the IMDG Code for ocean freight, IATA's Dangerous Goods Regulations for air) all build on.
The number answers "what substance is this" for emergency responders, carriers, and regulators who need a fast, language-independent lookup. It is not a measure of risk by itself — that's a separate field.
UN number vs. hazard class vs. packing group
Three fields work together on a dangerous goods shipment, and they answer different questions.
| Field | Answers | Example |
|---|---|---|
| UN number | What is this specific substance? | UN1203 |
| Hazard class | What kind of danger does it pose? | Class 3 (flammable liquid) |
| Packing group | How severe is the hazard? | PG II (medium danger) |
Two products in the same hazard class can carry different UN numbers, and the same UN number always maps to the same hazard class and (usually) the same packing group — the UN number is the lookup key, and the class and packing group are what you find once you look it up. A small number of U.S.-specific materials that have no UN Model Regulations entry get an "NA" number instead, and a separate "ID" number series exists for some materials offered specifically for air transport.
Where it lives in product data, and why catalog teams need it
The UN number appears in Section 14 (Transport Information) of a product's Safety Data Sheet, on the shipping papers and bill of lading, and — for shipments above regulatory thresholds — on the orange placard or diamond hazard label on the package itself, printed directly after "UN."
For a distributor or manufacturer moving chemicals, batteries, aerosols, or other regulated goods, the UN number is catalog data, not just a shipping-dock concern: it determines which carriers will accept the shipment, which packaging and labeling rules apply, and whether a product can move by air at all. A PIM or item master that stores the UN number, hazard class, and packing group per SKU lets a 3PL or carrier screen a shipment automatically instead of a warehouse worker reading the SDS by hand on every order. Products with no UN number are, by definition, not regulated as dangerous goods for transport — the absence of the field is itself meaningful data.
Frequently asked questions
Where do I find a product's UN number?
Section 14 (Transport Information) of the Safety Data Sheet. It's also printed on the dangerous goods shipping papers and, for shipments that require placarding, on the orange panel or hazard diamond on the package. If the SDS has no Section 14 entry, or Section 14 says "not regulated," the product has no UN number because it isn't classified as dangerous goods for transport.
Is a UN number the same as a hazard class?
No. The UN number identifies the specific substance or article; the hazard class describes the type of danger it presents (flammable, corrosive, toxic, and so on). The same UN number always points to the same hazard class, but the UN number is the lookup key — the class, along with the packing group, is information you retrieve from it, not a separate identifier for the same thing.
Do all products have UN numbers?
No. Only materials and articles that meet the UN Model Regulations' criteria for dangerous goods — explosives, flammable liquids and gases, corrosives, toxic and infectious substances, oxidizers, radioactive material, and certain batteries, among other classes — get a UN number. The large majority of manufactured goods are not regulated as dangerous goods for transport and carry no UN number at all.
What's the difference between UN, NA, and ID numbers?
UN numbers come from the UN Model Regulations and are recognized internationally. NA (North America) numbers are a small supplementary series the U.S. and Canada use for materials not covered by a UN entry, and they are generally not valid for international shipments. ID numbers are a narrower series used specifically for some materials offered for air transport. All three appear in the same column of the U.S. Hazardous Materials Table in 49 CFR 172.101.