What are the types of fire extinguishers?
There are five primary types of fire extinguisher, one for each class of fire: A, B, C, D and K, per the U.S. Fire Administration.
The U.S. Fire Administration writes it as five primary types, each designed to put out a different kind of fire, and says extinguishers hold different agents — water, carbon dioxide, dry chemical or wet chemical — depending on the fire they are meant for. NFPA lists the same five classes: Class A ordinary combustibles, Class B flammable liquids, Class C energized electrical equipment, Class D combustible metals, Class K cooking media.
Sources: U.S. Fire Administration, NFPA
This page is general information, not professional advice, and it is not legal advice. Fire code is adopted locally and your building's requirements come from your own fire marshal and your insurer, so the only schedule that governs your property is the one they give you in writing.
What each class of fire actually is
| Class | The fire | Where you find it |
|---|---|---|
| A | Ordinary combustibles — wood, paper, cloth | Offices, classrooms, assembly halls |
| B | Flammable and combustible liquids — grease, gasoline, oil, oil-based paint | Workshops, garages, storage and manufacturing areas |
| C | Energized electrical equipment plugged into an outlet | Anywhere with live equipment; the agent must not conduct electricity |
| D | Combustible metals | Industrial plants and laboratories |
| K | Vegetable oils, animal oils and fats in cooking appliances | Commercial kitchens — restaurants, cafeterias, catering |
Sources: U.S. Fire Administration, NFPA
Why a commercial kitchen needs a Class K unit of its own
The U.S. Fire Administration puts Class K where cooking oils and fats burn in cooking appliances, and says it is often found in commercial kitchens — restaurants, cafeterias and catering businesses. OSHA treats the same hazard as its own placement problem: where a potential fire hazard from combustible cooking media exists, Class K extinguishers must be installed at a maximum travel distance of thirty feet, less than half the distance allowed for ordinary combustibles.
Sources: U.S. Fire Administration, OSHA Evacuation Plans eTool
That thirty-foot number is the practical reason a kitchen ends up with a wall unit of its own rather than sharing the one in the corridor. It is also why the wet chemical extinguisher is the most expensive class to inspect — it is the one a kitchen cannot operate without.
The multipurpose extinguisher, and what it does not cover
The U.S. Fire Administration notes that multipurpose extinguishers labelled B-C or A-B-C can be used on most kinds of home fire, and that most home improvement stores carry a multipurpose unit covering Class A through Class C. What that label does not include is K. A multipurpose extinguisher in a commercial kitchen does not satisfy a Class K hazard, and a fire inspector will say so.
Source: U.S. Fire Administration
How to read the letters and numbers on the label
The U.S. Fire Administration spells out what the numbers mean, and they are not decoration. The number before the A is a multiple of 1.25 gallons of water. The number before the B is a multiple of the area, in square feet, of fire the unit can put out. So a label reading 1-A:10-B:C provides the equivalent of 1.25 gallons of water on a Class A fire, can handle a Class B fire up to ten square feet, and is safe on Class C — energized electrical equipment. C never carries a number, because it describes the agent rather than a tested fire size.
Source: U.S. Fire Administration
The A number is not decoration. NFPA's placement guidance ties it directly to how much floor one extinguisher is allowed to cover: the maximum floor area is the maximum area per unit of A multiplied by the numerical A rating, reaching a ceiling of 11,250 square feet. NFPA's own worked example is a 6-A extinguisher in an ordinary hazard occupancy, which comes out at 9,000 square feet.
Source: NFPA
That is the arithmetic behind how many units a building needs, and it is the arithmetic in the tool — work out how many fire extinguishers your building needs.
One label to check before you buy anything
The U.S. Fire Administration says to look for the UL Listed or ULC Listed mark, which shows the extinguisher is certified by a nationally recognized testing laboratory. Its other piece of buying advice is more practical than it sounds: choose the largest extinguisher a person can still safely and comfortably operate. A unit nobody can lift off the bracket is not protection.
Source: U.S. Fire Administration
Questions people ask next
- What are the five classes of fire extinguisher?
- Class A for ordinary combustibles, B for flammable liquids, C for energized electrical equipment, D for combustible metals and K for cooking oils and fats, per the U.S. Fire Administration and NFPA.
- What is a Class K fire extinguisher?
- The unit for vegetable and animal cooking oils and fats in cooking appliances, found in commercial kitchens. OSHA requires a maximum travel distance of thirty feet to one where that hazard exists.
- What does 1-A:10-B:C mean on a fire extinguisher?
- Per the U.S. Fire Administration, it provides the equivalent of 1.25 gallons of water on a Class A fire, handles a Class B fire up to ten square feet, and is safe on energized electrical equipment. The C never carries a number.
- Is an ABC extinguisher enough for a restaurant kitchen?
- No. The U.S. Fire Administration describes A-B-C multipurpose units as covering Class A through C. Cooking oils and fats are Class K, and that hazard needs its own extinguisher.
Written for building owners by Most Recommended Fire Protection, which measures which fire protection companies AI assistants actually recommend. Nobody can pay to be on those lists. How we measure.