Free Tool · CDL Hazmat
Hazmat Placard Lookup
Enter a UN/NA number to get the DOT placard class, proper shipping name, packing group, and hazard description. 50 most common materials — covers most CDL Hazmat exam questions.
Enter 4-digit UN number only (e.g. 1203 for Gasoline)
Common UN Numbers
Pro Insights
- ERG emergency response guide page number for this UN#:See in app
- Segregation requirements with other hazard classes:See in app
- Shipping paper description requirements (49 CFR):See in app
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How DOT Hazmat Placards Work
DOT hazmat placards are diamond-shaped warning signs required on vehicles transporting hazardous materials in quantities at or above specified thresholds. Federal regulations (49 CFR 172 Subpart F) require placards based on hazard class and quantity. For most hazard classes, placards are required when the vehicle carries 1,001 lbs or more of a hazardous material — or any quantity of a Poison Inhalation Hazard (PIH), Explosives 1.1, 1.2, or 1.3, or certain radioactive materials.
Each UN number uniquely identifies a hazardous material and maps to a hazard class, proper shipping name, and packing group. The packing group (I, II, or III) indicates the degree of hazard within a class: PG I is the greatest danger, PG III is the least. Not all materials have a packing group — gases are not packing group classified.
The CDL Hazmat endorsement exam tests knowledge of placarding requirements, hazard classes, the Emergency Response Guidebook (ERG), shipping paper requirements, and driver responsibilities. This lookup covers the 50 most common UN numbers that appear on the exam.
Frequently Asked Questions
How many DOT hazmat hazard classes are there?
There are 9 DOT hazard classes: Class 1 (Explosives), Class 2 (Gases), Class 3 (Flammable Liquids), Class 4 (Flammable Solids), Class 5 (Oxidizers/Organic Peroxides), Class 6 (Poisons/Infectious Substances), Class 7 (Radioactive Materials), Class 8 (Corrosives), and Class 9 (Miscellaneous Dangerous Goods). Some classes have sub-divisions — explosives, for example, have divisions 1.1 through 1.6.
What is the difference between a UN number and an NA number?
UN numbers are international identifiers recognized by the United Nations. NA numbers are North America-only identifiers used for materials not assigned a UN number or for specific domestic use. Most common hazmat materials use UN numbers; NA numbers appear only in US and Canadian regulations.
When is a placard required vs. just a label?
Labels are placed on individual packages and are required regardless of quantity. Placards go on the vehicle itself and are generally required at the 1,001-lb threshold for most classes. Some materials — Division 2.3 poison gas, Division 6.1 PIH, and certain radioactive materials — require placards in any quantity.
What is the ERG and why does it matter for the CDL Hazmat exam?
The Emergency Response Guidebook (ERG) is published by PHMSA and provides first-responder guidance for hazmat incidents. Drivers must carry shipping papers and know how to locate the ERG guide page for their load. The CDL Hazmat exam tests your ability to read shipping papers, identify the hazard class, and find the correct ERG response guide.