# UN Number

*Last updated: 2026-06-26*

> The UN Number identifies a hazardous substance or article unambiguously across every mode of transport.

The UN Number identifies a hazardous substance or article unambiguously across every mode of transport. Assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods, this four-digit code appears in ADR (road), RID (rail), IMDG (sea), and IATA DGR (air) regulations alike, making it the universal language of dangerous goods handling. In daily freight operations, the UN Number must appear on shipping documents, hazard labels, and—where required—on the orange hazard placards affixed to vehicles or containers. Together with the hazard class and packing group, it determines packaging specifications, segregation rules, and emergency response procedures. Missing or incorrect UN Numbers routinely result in cargo rejection, port holds, or regulatory penalties.

**Source:** [https://unece.org/transport/dangerous-goods](https://unece.org/transport/dangerous-goods)

## Quick Facts

| Property | Value |
|---|---|
| Term | UN Number |
| Language | EN |
| Word count | 113 |
| Last updated | 2026-06-26 |
| Source | https://unece.org/transport/dangerous-goods |

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