Fire Extinguisher Coverage Calculator

Calculates the minimum number of portable fire extinguishers needed for a floor area, per NFPA 10 (Standard for Portable Fire Extinguishers) hazard classification, floor-area coverage, and maximum travel distance.

Fire Class

Occupancy Hazard Classification

Floor Area to Protect (sq ft)

—

Minimum Extinguisher Rating

0 ft

Max Travel Distance

Minimum Extinguishers Required

Formula Reference

Extinguishers by Floor Area = ⌈ Floor Area ÷ Max Area per Unit ⌉ (Class A only \u2014 NFPA 10 Table 6.2.1.1)
Grid Spacing (travel-distance based) = Max Travel Distance ÷ √2
Extinguishers by Travel Distance = ⌈ Floor Area ÷ Grid Spacing² ⌉
Required = the larger of the two figures (both must be satisfied)

NFPA 10 Table 6.2.1.1 — Class A

Light Hazard	2-A min · 3,000 ft²/unit · 75 ft travel
Ordinary Hazard	2-A min · 1,500 ft²/unit · 75 ft travel
Extra Hazard	4-A min · 1,000 ft²/unit · 75 ft travel

Class B & K Travel Distance

Class B	2-A:10-B:C (ordinary) / 4-A:40-B:C (extra) min · 30–50 ft travel depending on rating (NFPA 10 Table 6.3.1.1)
Class K	30 ft travel from cooking appliances (must supplement, not replace, Class A/B/C coverage — NFPA 10 §5.6.2 / NFPA 96)

Note: the 75 ft Class A travel distance applies at all hazard levels \u2014 what changes with hazard level is the minimum rating and maximum floor area per unit, not the travel distance itself.

Based on NFPA 10 (Standard for Portable Fire Extinguishers) and OSHA 29 CFR 1910.157. The floor-area/travel-distance method shown is a planning-level estimate for open, regularly-shaped floor areas — actual placement must account for the real floor plan, obstructions, aisles, and doorways (travel distance is walked distance, not straight-line), and must be verified by a qualified person or the Authority Having Jurisdiction (AHJ). Class B extinguisher rating and exact travel distance depend on the specific hazard and flammable liquid quantity — consult NFPA 10 Table 6.3.1.1 directly for that determination. For customized calculators tailored to your organization, please contact Impact Tech Solutions.