What fire extinguisher should I keep in my vehicle?

When it comes to vehicle safety, a fire extinguisher is one of the most overlooked pieces of equipment. Many drivers aren’t sure what size or type they need—or even how to read the rating on the label. Here’s a clear guide to understanding UL ratings and how they match up to cars, work trucks, and recreational vehicles, plus what is recommended or required for your needs.

Understanding UL Fire Extinguisher Ratings:

Every portable fire extinguisher carries a UL (Underwriters Laboratories) rating. This code tells you what kinds of fires it can handle and how much fire-fighting capacity it has.

Note: The letters indicate the type of fire:

A : For ordinary combustibles (like wood, cloth, or paper)

B : for flammable liquids (gasoline, oil)

C : for energized electrical equipment

The numbers in front of the letters indicate capacity. For A, each “1A” equals roughly 1.25 gallons of water equivalent. For B, “10B” means the extinguisher can cover about 10 square feet of burning liquid in testing. The C has no number; it just means the unit is safe to use on live electrical circuits.

For example, a “1A:10B:C” unit can handle small wood or fabric fires, about 10 square feet of liquid fire, and is safe on electrical fires.

Which Fire Extinguisher Do I Need for My Vehicle?

For private vehicles such as passenger cars and SUVs, there’s no universal legal requirement for a fire extinguisher. But because cars have gasoline and plenty of wiring, at minimum a 5B:C should be mounted, but experts recommend at least a 1A:10B:C unit. It’s small enough to mount under a seat but powerful enough for most roadside emergencies.

Commercial pickups, work trucks and service vans often carry fuels, oils, or inverters, making a larger unit worthwhile. A 1A:10B:C is the minimum practical size, but a 3A:40B:C offers substantially more protection and aligns well with the hazards these vehicles face daily. 

Recreational Vehicles (RVs) have to meet the National Fire Protection Association (NFPA) standard for RVs (NFPA 1192):

- Motorhomes must carry at least a 10B:C rated extinguisher.
- Towable RVs (travel trailers, fifth-wheels) need at least a 5B:C unit if they have fuel-burning equipment or 120/240 V systems.
- Many owners go beyond the minimum and install a 1A:10B:C or even 3A:40B:C unit for added Class-A capacity.

Commercial Trucks and Buses Federal law (49 CFR §393.95) requires commercial motor vehicles to carry portable fire extinguishers:

- Non-hazardous cargo CMVs must have at least a 5B:C rated extinguisher.
- Placarded hazardous materials vehicles must have at least a 10B:C rated extinguisher.
- Extinguishers must be securely mounted, readily accessible, properly labeled with the UL rating, and use an agent that does not require freeze protection.

State-Specific Variations - Some states add extra requirements, especially for passenger-carrying vehicles and school buses. Because state rules can vary widely, it’s always wise to check your state DOT, DMV, or fire marshal’s office for the latest requirements.

Choosing Between 5B:C, 1A:10B:C, and 3A:40B:C

- A 5B:C unit is small and meets the minimum for many commercial and towable RV requirements but has limited discharge time.
-A 1A:10B:C unit is a balanced choice for passenger cars and light work vehicles, adding Class-A capability for interior materials.
-A 3A:40B:C unit offers substantially more agent and range, ideal for work trucks, service vans, or larger RVs—provided you have a sturdy mount.

Regardless of size, mount your extinguisher where you can grab it quickly (driver area or by the main door) and secure it firmly so it doesn’t become a projectile.

To make safety easier, we’ve put together vehicle-specific safety kits that include an appropriately rated fire extinguisher and mounting bracket. If you’d like to browse or purchase one of these kits, simply click HERE to view our recommended products, and get your vehicle ready for the road.