A UN number is a four-digit number assigned by the UN Committee of Experts on the Transport of Dangerous Goods. It identifies a dangerous substance, or a group of substances, for transport by sea, air, road and rail.
Emergency services, port staff and carriers use it to look up the hazard and the right response at once, without needing to know the chemistry.
How UN numbers work
Some UN numbers cover one specific substance. UN1090 is acetone, UN1823 is sodium hydroxide in solid form, and UN1824 is sodium hydroxide solution. The same chemical can have different numbers depending on its form.
Other numbers are generic entries, marked n.o.s. for not otherwise specified. UN1993 covers flammable liquids not listed elsewhere, and UN3082 covers environmentally hazardous liquids not listed elsewhere. When a generic entry is used, the technical name of the hazardous component is usually added in brackets after the proper shipping name.
Each UN number comes with a proper shipping name, a class and, for most substances, a packing group. All four must be consistent across every document. See the IMDG classes for what the class means.
Where the UN number appears
- On each package, next to the proper shipping name, with the letters UN in front, for example UN 1824.
- On the container, on the placards or orange panels where the rules require them.
- On the dangerous goods declaration, alongside the class, packing group and quantity.
- In section 14 of the safety data sheet.
- In the booking request to the shipping line, which uses it to check acceptance.
Do not confuse it with the UN packaging mark
UN-approved packaging carries its own mark, beginning with the UN symbol and a code such as 1A1 or 1H1. That mark certifies the packaging, not the contents. A drum may carry both: the UN packaging mark embossed or printed by the drum maker, and the UN number of the product marked by the shipper. Read UN-approved packaging for how to check the packaging mark.
What to check before shipment
- The UN number on the SDS matches the one on the DG declaration and the booking.
- The proper shipping name is the exact wording linked to that UN number.
- Every package is marked, and marks are durable and readable after handling.
- Leftover marks from a previous cargo have been removed from reused drums and IBCs.
- The packaging is approved for the class and packing group of that UN number.
- The UN number used for a mixture reflects the mixture's own hazards, not just those of its main ingredient. A change in recipe can change the number.
Next step
The shipper is responsible for correct marking, and your forwarder will confirm carrier requirements. We inspect marks and labels at loading. To start, book a free sourcing review.