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DOT hazard classes and placard lookup
DOT sorts hazardous materials into 9 hazard classes: 1 explosives, 2 gases, 3 flammable liquids, 4 flammable solids, 5 oxidizers and organic peroxides, 6 poisons and infectious substances, 7 radioactive material, 8 corrosives and 9 miscellaneous (49 CFR 173.2). The class decides the placard. Table 1 materials, such as poison gas and dangerous when wet, need placards at any quantity; Table 2 materials need them once a highway or rail vehicle carries 1,001 lb or more of them in total (49 CFR 172.504). Enter what is on your truck below to see which placards it needs.
Updated October 12, 2026
Source: 49 CFR Parts 172, 173, 174 and 177 on eCFR, current to October 8, 2026. Fixed sites use a different system: see the NFPA 704 diamond maker.
The 9 DOT hazard classes and their divisions
| Class / division | Name | In plain words | Definition |
|---|---|---|---|
| 1 / 1.1 | Explosives with a mass explosion hazard | An explosion that affects almost the entire load at once. | 49 CFR 173.50(b)(1) |
| 1 / 1.2 | Explosives with a projection hazard | Throws fragments, but does not explode as a mass. | 49 CFR 173.50(b)(2) |
| 1 / 1.3 | Explosives with predominantly a fire hazard | A fire hazard with a minor blast or projection hazard, or both, but no mass explosion. | 49 CFR 173.50(b)(3) |
| 1 / 1.4 | Explosives with no significant blast hazard | A minor explosion hazard, mostly confined to the package. No large fragments thrown far. | 49 CFR 173.50(b)(4) |
| 1 / 1.5 | Very insensitive explosives; blasting agents | Could explode as a mass, but so insensitive that starting it in normal transport is very unlikely. | 49 CFR 173.50(b)(5) |
| 1 / 1.6 | Extremely insensitive detonating substances | Extremely insensitive articles with no mass explosion hazard; the risk is limited to one article. | 49 CFR 173.50(b)(6) |
| 2 / 2.1 | Flammable gas | A gas at 68 F that ignites in air at 13% or less by volume, or has a flammable range of at least 12 points. | 49 CFR 173.115(a) |
| 2 / 2.2 | Non-flammable compressed gas | A gas under at least 29 psig at 68 F, or a liquefied or cryogenic gas, that is not flammable or poisonous. Includes asphyxiant and oxidizing gases. | 49 CFR 173.115(b) |
| 2 / 2.3 | Poisonous gas | A gas known to be so toxic to people that it is a health hazard in transport, or presumed so from animal tests. Assigned Hazard Zone A, B, C or D. | 49 CFR 173.115(c) |
| 3 | Flammable liquid | A liquid with a flash point of 140 F (60 C) or lower, with listed exceptions. | 49 CFR 173.120(a) |
| 3 (combustible) | Combustible liquid | A liquid with a flash point above 140 F and below 200 F (93 C) that fits no other class. A flammable liquid with a flash point at or above 100 F can be reclassed as combustible for ground transport. | 49 CFR 173.120(b) |
| 4 / 4.1 | Flammable solid | Desensitized explosives, self-reactive materials, readily combustible solids and similar materials. | 49 CFR 173.124(a) |
| 4 / 4.2 | Spontaneously combustible material | Pyrophoric material that ignites within 5 minutes of contact with air, or self-heating material that can heat up until it ignites. | 49 CFR 173.124(b) |
| 4 / 4.3 | Dangerous when wet material | In contact with water it can become flammable on its own or give off flammable or toxic gas faster than 1 liter per kilogram per hour. | 49 CFR 173.124(c) |
| 5 / 5.1 | Oxidizer | A material that, usually by giving off oxygen, can cause or speed up the burning of other materials. | 49 CFR 173.127(a) |
| 5 / 5.2 | Organic peroxide | An organic compound with the -O-O- structure, a derivative of hydrogen peroxide, with listed exceptions. Types A to G; Type A is forbidden. | 49 CFR 173.128(a) |
| 6 / 6.1 | Poisonous materials | A material, other than a gas, so toxic to people that it is a health hazard in transport, or presumed so from oral, skin or inhalation toxicity tests. | 49 CFR 173.132(a) |
| 6 / 6.2 | Infectious substance | A material known or reasonably expected to contain a pathogen that can cause disease in people or animals. | 49 CFR 173.134(a) |
| 7 | Radioactive material | Material containing radionuclides where both the activity concentration and the total activity in the shipment exceed set limits. | 49 CFR 173.403 |
| 8 | Corrosive material | A liquid or solid that causes irreversible damage to skin, or a liquid that severely corrodes steel or aluminum. | 49 CFR 173.136(a) |
| 9 | Miscellaneous hazardous material | A hazard in transport that fits no other class, including elevated temperature materials, hazardous substances, hazardous wastes and marine pollutants. | 49 CFR 173.140 |
Names from the table in 49 CFR 173.2; plain-word summaries of the definitions in Part 173, Subpart D. The full definitions include tests and exceptions not repeated here.
A material can meet more than one definition. 49 CFR 173.2a sets which hazard wins as the primary class; the others become subsidiary hazards, shown with subsidiary labels and sometimes extra placards.
Placard chart: which placard for which class
| Category | Placard | When required | What it looks like |
|---|---|---|---|
| 1.1 Explosives | EXPLOSIVES 1.1 | Table 1: any quantity | Orange background; black exploding-bomb symbol, text, division number and inner border. |
| 1.2 Explosives | EXPLOSIVES 1.2 | Table 1: any quantity | Orange background; black exploding-bomb symbol, text, division number and inner border. |
| 1.3 Explosives | EXPLOSIVES 1.3 | Table 1: any quantity | Orange background; black exploding-bomb symbol, text, division number and inner border. |
| 1.4 Explosives | EXPLOSIVES 1.4 | Table 2: 1,001 lb or bulk | Orange background; black text, numerals and inner border. The 1.4 is at least 2.5 in (64 mm) high. |
| 1.5 Blasting agents | EXPLOSIVES 1.5 | Table 2: 1,001 lb or bulk | Orange background; black text, numerals and inner border. The 1.5 is at least 2.5 in (64 mm) high. |
| 1.6 Extremely insensitive | EXPLOSIVES 1.6 | Table 2: 1,001 lb or bulk | Orange background; black text, numerals and inner border. The 1.6 is at least 2.5 in (64 mm) high. |
| 2.1 Flammable gas | FLAMMABLE GAS | Table 2: 1,001 lb or bulk | Red background; white flame symbol, text, class number and inner border. |
| 2.2 Non-flammable gas | NON-FLAMMABLE GAS | Table 2: 1,001 lb or bulk | Green background; white gas-cylinder symbol, text, class number and inner border. |
| 2.2 Oxygen (compressed or refrigerated liquid) | NON-FLAMMABLE GAS | Table 2: 1,001 lb or bulk | Green background; white gas-cylinder symbol, text, class number and inner border. |
| 2.3 Poison gas | POISON GAS | Table 1: any quantity | White background with a black upper diamond; white skull-and-crossbones symbol in the black area; black text, class number and inner border. |
| 3 Flammable liquid | FLAMMABLE | Table 2: 1,001 lb or bulk | Red background; white flame symbol, text, class number and inner border. GASOLINE may replace the word on a gasoline cargo or portable tank. |
| Combustible liquid | COMBUSTIBLE | Table 2: 1,001 lb or bulk | Red background; white flame symbol, text, class number and inner border. FUEL OIL may replace the word on a fuel oil cargo or portable tank. |
| 4.1 Flammable solid | FLAMMABLE SOLID | Table 2: 1,001 lb or bulk | White background with seven vertical red stripes; black flame symbol, text, class number and inner border. |
| 4.2 Spontaneously combustible | SPONTANEOUSLY COMBUSTIBLE | Table 2: 1,001 lb or bulk | White upper half, red lower half; black flame symbol, text, class number and inner border. |
| 4.3 Dangerous when wet | DANGEROUS WHEN WET | Table 1: any quantity | Blue background; white flame symbol, text, class number and inner border. |
| 5.1 Oxidizer | OXIDIZER | Table 2: 1,001 lb or bulk | Yellow background; black flame-over-circle symbol, text, division number and inner border. |
| 5.2 Organic peroxide, Type B, temperature controlled | ORGANIC PEROXIDE | Table 1: any quantity | Red top half, yellow lower half; black text, division number and inner border; the flame symbol may be black or white. |
| 5.2 Organic peroxide, other | ORGANIC PEROXIDE | Table 2: 1,001 lb or bulk | Red top half, yellow lower half; black text, division number and inner border; the flame symbol may be black or white. |
| 6.1 Poisonous by inhalation (PIH) | POISON INHALATION HAZARD | Table 1: any quantity | White background with a black upper diamond; white skull-and-crossbones symbol in the black area; black text, class number and inner border. |
| 6.1 Poison, other than PIH | POISON | Table 2: 1,001 lb or bulk | White background; black skull-and-crossbones symbol, text, class number and inner border. TOXIC may replace POISON. |
| 6.2 Infectious substance | None | Not placarded | Not placarded under 172.504(e). |
| 7 Radioactive, Yellow III label | RADIOACTIVE | Table 1: any quantity | Yellow upper triangle, white lower portion; black trefoil symbol, text, class number and inner border. |
| 7 Radioactive, White I or Yellow II label | None | Not placarded | See Table 1 footnote in 172.504(e). |
| 8 Corrosive | CORROSIVE | Table 2: 1,001 lb or bulk | White upper triangle, black lower portion; white text and class number; black symbol and inner border. |
| 9 Miscellaneous | CLASS 9 | Table 2: 1,001 lb or bulk | White background with seven black vertical stripes on the top half; the class number 9, underlined, at the bottom. |
From 49 CFR 172.504(e) Tables 1 and 2 and the placard design sections 172.521 to 172.560. Colors and symbols described in words; the regulation’s drawings govern.
How placarding works
Find each material’s class in column 3 of the Hazardous Materials Table, 49 CFR 172.101. Do not guess it from the product name.
Table 1 or Table 2? Explosives 1.1 to 1.3, poison gas (2.3), dangerous when wet (4.3), Type B temperature-controlled organic peroxides, poison inhalation hazard materials and Radioactive Yellow III packages are Table 1: placard at any quantity.
Add up the Table 2 materials in non-bulk packages on the vehicle, by gross weight. Under 1,001 lb in total, a highway or rail vehicle needs no placards for them (172.504(c)). At 1,001 lb or more, each one gets its placard.
Bulk packaging is placarded at any quantity, Table 1 or Table 2. A bulk packaging holds more than 119 gallons of liquid, or as 49 CFR 171.8 defines for solids and gases.
Apply the exceptions in 172.504(f): show only the lowest explosives division, drop NON-FLAMMABLE GAS when FLAMMABLE GAS is shown, drop POISON when POISON GAS or POISON INHALATION HAZARD is shown, and CLASS 9 is optional within the US.
Put a placard on each side and each end of the vehicle (172.504(a)).
The 1,001 lb rule and the DANGEROUS placard, worked through
600 lb of a Class 3 flammable liquid and 300 lb of a Class 8 corrosive, both in drums: 900 lb of Table 2 material, so placards needed: none.
The same load with 500 lb of the corrosive: 1,100 lb in total, so placards needed: FLAMMABLE and CORROSIVE. Because two Table 2 categories need different placards, one DANGEROUS placard may replace both (172.504(b)).
40 lb of a 2.3 poison gas in cylinders: Table 1, so POISON GAS at any quantity.
DANGEROUS stops working for a category once 2,205 lb (1,000 kg) or more of it is loaded at one facility: that category gets its own placard next to the DANGEROUS one (172.504(b)).
Bulk packagings, and materials that need a POISON INHALATION HAZARD or POISON GAS placard under 172.505(a), do not count toward the 1,001 lb: they are placarded on their own (PHMSA letters 98-0424 and 02-0043).
Placard size, color and the symbols in this tool
A placard is a square on point at least 250 mm (9.84 in) on each side, with an inner border about 12.5 mm in from the edge, and class numbers at least 41 mm (1.6 in) high (49 CFR 172.519(c)). Colors must fall inside PHMSA’s color tolerance chart or the Pantone values in 172.407(d). The placards this tool draws are simplified illustrations to help you recognize them, not print-ready art: buy placards from a placard supplier.
DOT placards and NFPA 704 diamonds are different systems
DOT placards are for transportation: trucks, rail cars, freight containers and bulk packagings, under 49 CFR. The NFPA 704 diamond, with its blue, red, yellow and white quadrants, marks fixed facilities such as buildings, rooms and tanks for emergency responders. A warehouse door may carry an NFPA diamond while the truck at the dock carries DOT placards. Make a diamond for a fixed site with the NFPA 704 diamond maker.
Common questions
What is the difference between a label and a placard?
Labels go on packages (49 CFR Part 172, Subpart E); placards go on the vehicle, freight container or bulk packaging. This tool covers placards.
Do limited quantities need placards?
No. Materials offered as limited quantities, small quantities under 173.4, and combustible liquids in non-bulk packagings are outside the placarding rules (49 CFR 172.500(b)).
Does Class 9 need a placard?
Not for transportation within the US, but a bulk packaging must still show its identification number on a CLASS 9 placard, an orange panel or a white square on point (172.504(f)(9)). Whether non-bulk Class 9 weight counts toward another material’s 1,001 lb is unsettled: a 1997 RSPA letter (97-0099) said no, and a request filed with PHMSA in August 2026 (26-0111) asks whether that still stands. When only the Class 9 weight takes a load past 1,001 lb, the tool shows the other placards as optional rather than required.
Where do I write this on the bill of lading?
The shipping description, with the UN number, proper shipping name, class and packing group, goes on the shipping papers. The bill of lading generator has hazmat lines and the emergency response phone number.
Limits
This is a reference aid, not hazmat training, and the regulations govern. It does not cover vessel or air rules beyond noting where they differ, highway route-controlled radioactive shipments, or state and local rules. Check each material in the Hazardous Materials Table for its class, packing group and special provisions, and train your hazmat employees as 49 CFR 172.704 requires.
Related tools
Sources
49 CFR 172.407, label specifications, including color tolerances
49 CFR 173.150, exceptions for Class 3 and combustible liquids
PHMSA interpretation 98-0424, Table 2 weight in bulk or PIH packages and the 1,001 lb exception
PHMSA interpretation 02-0043, bulk and non-bulk weights are not added
PHMSA interpretation request 26-0111 (August 2026), non-bulk Class 9 weight
WHERE MORSA FITS
Shipping hazmat? Check the papers before the truck does.
Morsa checks the shipping papers against the order before the truck arrives, and asks your team or the supplier about anything that does not match while there is still time to fix it. It works in email, Teams, WhatsApp or whatever you already run on, and reads from your ERP.
