How many fire extinguishers do I need?
Enough that nobody walks more than seventy-five feet to reach one for ordinary combustibles, or fifty feet for flammable liquids, per OSHA.
OSHA sets the requirement as a walk rather than a count. Portable extinguishers must be distributed so the travel distance for employees to any extinguisher is seventy-five feet or less for Class A fires, and fifty feet or less from a Class B hazard area. Where combustible cooking media are present, the maximum travel distance drops to thirty feet.
This page is general information, not professional advice, and it is not legal advice. Fire code is adopted locally, so the schedule that governs your building comes from your own fire marshal and your insurer.
The second rule, which catches large open floors
Travel distance is usually the binding constraint, but not always. NFPA sets a maximum floor area a single Class A extinguisher is allowed to cover, tied to the numerical A rating on its label and to the hazard level of the space, topping out at 11,250 square feet. Its own worked example is a 6-A extinguisher in an ordinary hazard occupancy, which comes out at 9,000 square feet. You follow whichever of the two rules is more restrictive.
Source: NFPA
OSHA's guidance gives the light-hazard version of the same idea in plainer form: NFPA recommends that locations such as offices, classrooms and assembly halls containing mainly Class A combustible materials have one 2-A extinguisher for every 3,000 square feet.
Source: OSHA Evacuation Plans eTool
Why a big warehouse needs more than the walk suggests
NFPA makes the point directly: in a wide open space such as a large warehouse you cannot take advantage of the full seventy-five feet, because the floor-area limit bites first. And spacing units 150 feet apart to make the seventy-five feet work in a straight line leaves corners that are further than seventy-five feet away, because rooms are rectangles. NFPA's published answer is to place extinguishers every 106 feet, which fits the shape of a real room.
Source: NFPA
The mistake that puts a compliant building out of compliance
NFPA is explicit that the distance measured has to be the actual distance a person would need to walk, and that occupants are not expected to walk through walls. That is the rule a fit-out breaks. Put up a partition, lock a connecting door, or stack pallets across an aisle, and the walk changes even though nothing was moved off the wall.
Source: NFPA
- Every floor gets its own count. A stairwell is not a short walk.
- The kitchen is its own problem, at thirty feet rather than seventy-five.
- A workshop, garage, warehouse, storage or service area is a Class B area at fifty feet, even inside an otherwise ordinary building.
- Class D hazards — combustible metals — must have an extinguisher not more than seventy-five feet from the hazard itself.
To turn your own square footage into a starting number, use the fire extinguisher calculator.
What the number from any rule is, and is not
It is a floor, not a verdict. Your local fire code, your insurer and the way your building is actually laid out can all push the count up, and the only number that governs your property is the one your fire marshal signs off on. What the rules above give you is the figure to walk in with, so that a proposal for eight units in a building the rules suggest needs three is a conversation rather than a surprise.
Questions people ask next
- How many fire extinguishers does my building need?
- Enough that nobody walks more than seventy-five feet to one for ordinary combustibles, fifty feet from a flammable-liquid hazard, and thirty feet where cooking oils are used — and enough to stay under NFPA's floor-area cap per unit.
- How much floor can one fire extinguisher cover?
- NFPA ties it to the A rating on the label and the hazard level, capped at 11,250 square feet. Its worked example of a 6-A unit in an ordinary hazard occupancy comes out at 9,000 square feet.
- How far apart should fire extinguishers be?
- NFPA publishes 106 feet as the practical spacing. Placing them 150 feet apart satisfies the seventy-five-foot rule in a straight line but leaves corners of a rectangular room out of reach.
- Does a commercial kitchen need its own extinguisher?
- Yes. Where a fire hazard from combustible cooking media exists, OSHA sets a maximum travel distance of thirty feet to a Class K extinguisher — less than half the ordinary allowance.
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.