Skip to main content
Calcimator

Fire Extinguisher Placement Calculator

Calculate fire extinguisher count and spacing by hazard class per NFPA 10.

About this calculator

NFPA 10, the Standard for Portable Fire Extinguishers, governs portable fire extinguisher placement in the US, and this calculator's maximum travel distances are drawn directly from it: 75 ft for all three Class A tiers (Light, Ordinary, and Extra Hazard), 50 ft for Class B, and 30 ft for Class K (commercial kitchens). Coverage per extinguisher is derived differently by class: for Class B and Class K it works backward from the travel distance to a circular coverage area (area = pi times travel-distance squared). For all three Class A tiers -- including the Ordinary Hazard default -- it instead uses NFPA 10's maximum floor-area-per-unit figure directly (11,250 sq ft), which is not a travel-radius circle.

Either way, it divides the entered floor area by that coverage figure (rounding up) to estimate how many extinguishers each floor needs. This is a simplified planning model, not a literal reproduction of NFPA 10 Table 6.2.1.1 -- the official standard also varies minimum extinguisher rating and maximum floor area per unit by hazard tier in ways this calculator approximates rather than reproduces exactly (for example, official minimum Class A ratings are 2-A for both Light and Ordinary Hazard, not a tiered 2-A/3-A split), and Class K's specific numeric rating isn't governed by the same A/B numeric scale at all. Use this tool to rough out a placement plan and unit count, then confirm exact counts, ratings, and mounting heights against the current NFPA 10 edition and your local fire marshal or a licensed fire protection engineer before installation.

Inputs

sq ft

Results

Extinguishers per Floor

1

Total Extinguishers

2

Max Travel Distance (ft)75
Coverage per Unit (sq ft)11,250
Min Rating Class3
Total Purchase & Install Cost$150.00
Annual Maintenance Cost$30.00
Min Rating2-A

Figures current as of 2026. Source: National Fire Protection Association, NFPA 10, Standard for Portable Fire Extinguishers

How to Use This Calculator
  1. Enter Floor Area (sq ft) and Number of Floors for the building.
  2. Select the Hazard Class: Light, Ordinary, or Extra Hazard (Class A), Class B (flammable liquids), or Class K (commercial kitchen).
  3. Review Extinguishers per Floor and Total Extinguishers.
  4. Use Max Travel Distance (ft) and Coverage per Unit (sq ft) to plan physical placement, then confirm final counts and ratings against the current NFPA 10 edition and your local fire marshal.

What each input means

Floor Area (sq ft)
Total floor area per floor.
Hazard Class
Occupancy hazard classification for the space being protected.
Number of Floors
Total building floors requiring extinguishers.

What each result means

Min Rating
Minimum extinguisher rating for the selected hazard class, on that class's own scale (A, B, or a Class K listing). Class A minimums are 2-A for both Light and Ordinary Hazard; the numeric Min Rating Class above is this model's tiered approximation.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Floor Area (sq ft) = 10000, Hazard Class = 2, Number of Floors = 2 = 3 input(s) provided
  2. Calculate Extinguishers per Floor
    Extinguishers per Floor
    1 = 1
  3. Calculate Total Extinguishers
    Total Extinguishers
    2 = 2
  4. Calculate Max Travel Distance
    75 = 75
  5. Calculate Coverage per Unit
    11250 = 11250

Figures and sources

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Why does a commercial kitchen need a shorter extinguisher travel distance than an office?

Class K fires (cooking oils and fats) can flash back or re-ignite fast, and the wet-chemical agent used to fight them needs to be applied quickly and correctly, so NFPA 10 sets a shorter 30 ft maximum travel distance for kitchens versus 75 ft for Class A office and general-occupancy hazards. The shorter distance means an occupant is never far from an extinguisher when seconds matter most.

Does a taller building always need more extinguishers than a single-story one?

Yes, proportionally -- this calculator multiplies the extinguishers required per floor by the Number of Floors entered, since NFPA 10's coverage requirements apply separately to each floor rather than to the building's total square footage combined. Two identical floors each need their own full complement of correctly spaced extinguishers, not half as many each.

How is Class B extinguisher spacing different from Class A spacing?

Class B (flammable liquid) hazards get a shorter 50 ft maximum travel distance in this calculator versus 75 ft for Class A hazards, reflecting how quickly a flammable- liquid fire can spread and how important fast access is. Class K (commercial kitchens) is shorter still, at 30 ft, for the same reason applied to an even faster-developing fire type.

Is this calculator's extinguisher count a substitute for a fire marshal's approval?

No -- treat it as a planning estimate to rough out budget and layout before installation, not a code-compliance guarantee. NFPA 10's official tables set minimum ratings and maximum floor area per unit with more nuance than this simplified model captures, and final placement, mounting height, and unit count should always be confirmed against the current NFPA 10 edition and approved by the local Authority Having Jurisdiction.

Related Calculators

The questions that sit next to this one — chosen by subject, including calculators filed under a different category.

Fire Safety

Fire Sprinkler Design Calculator

Calculate sprinkler head count, spacing, design density, and pipe sizing per NFPA 13.

Fire Safety

Fire Egress Calculator

Calculate exit width, number of exits, and travel distance based on occupant load per IBC.

Fire Safety

Smoke Detector Spacing Calculator

Calculate smoke detector grid layout and spacing for different ceiling types per NFPA 72.

Construction Electrical

Fire Alarm Initiating Device Calculator

Smoke detector, heat detector, and pull station count from floor plan per NFPA 72.

More in Safety, Compliance & Emergency.