UN number hazmat lookup.

How to read a UN number entry

A UN number is a four-digit identifier assigned to a hazardous substance or group of substances under the United Nations dangerous goods system, written UN1203 for gasoline. In the United States, the Pipeline and Hazardous Materials Safety Administration (PHMSA) publishes the Hazardous Materials Table in 49 CFR 172.101, which pairs each identification number with a proper shipping name, a hazard class or division, a packing group and the labels required. This tool searches the UN-numbered rows of that table, 2,424 entries covering UN0004 to UN3550, as published in the eCFR on October 1, 2026. Rows with NA or ID numbers are not included, nor is the second half of the table with packaging and quantity columns.

The columns shown

Hazard class is shown with the name given in 49 CFR 173.2. For explosives the table adds a compatibility group letter, so 1.1D is division 1.1 (mass explosion hazard) with group D. Packing group is the Roman numeral in column 5 and is blank for gases, explosives and some other classes. Label codes are the hazard labels the package must bear, so a primary class plus any subsidiary hazards, such as 8, 3 for a corrosive that is also flammable. A symbol in the first column carries its own meaning: for example G means technical names must be added to the shipping description, and W or A mean the material is regulated only by vessel or only by aircraft.

Worked examples

UN1203 returns gasoline, class 3, packing group II, label 3. UN1017 returns chlorine, class 2.3 poisonous gas, with labels 2.3, 5.1 and 8. UN3480 returns lithium ion batteries, class 9. A single UN number can have several rows because the same number covers different shipping names or packing groups; UN1950 aerosols appears as separate flammable, non-flammable, corrosive and poison descriptions, and this tool shows each.

Limits you must respect

This is a reference lookup, not classification or shipping advice. The proper shipping name, packaging, quantity limits and exceptions depend on the exact material, its concentration and the mode of transport, and the table itself points to special provisions you must read. Training, shipping papers, marking and placarding requirements apply to anyone who offers hazardous materials for transport. Rules change; the live eCFR text controls. Nothing you type here leaves your browser.

Sources (each opened 2026-10-19): eCFR, 49 CFR 172.101 Hazardous Materials Table (full-text XML, up to date as of 2026-10-01; symbols in paragraph (b)); eCFR, 49 CFR 173.2 Hazardous material classes and index to hazard class definitions (class and division names).

FAQ

How do I look up a UN number for hazmat shipping?

Type the four digits, such as 1203 or UN1203, and the tool lists every UN-numbered row of the 49 CFR 172.101 Hazardous Materials Table with that number, including its proper shipping name, hazard class and packing group.

What do the hazard classes mean?

Class 1 is explosives, 2 gases, 3 flammable and combustible liquids, 4 flammable solids and related materials, 5 oxidizers and organic peroxides, 6 poisonous and infectious materials, 7 radioactive material, 8 corrosives and 9 miscellaneous hazardous material, as named in 49 CFR 173.2.

Why does one UN number show several rows?

The table lists a separate row for each proper shipping name or description, and some UN numbers cover several. UN1950 aerosols, for example, has separate flammable, non-flammable, corrosive and poison descriptions.

Does this include NA and ID numbers?

No. This tool covers UN-numbered entries only. Table rows identified by NA or ID numbers are not included, so check the live table for those.

Can I use this to classify or ship dangerous goods?

No. It is a reference to the published table. Classification, packaging, quantity limits, marking and training depend on the exact material and mode, so read the full regulation and follow your carrier requirements.

How current is the data?

It was taken from the eCFR version of 49 CFR 172.101 that was up to date as of October 1, 2026. The regulation is amended from time to time, so the live eCFR text controls.