Fire Extinguisher Coverage Calculator
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) |
Methodology, interpretation & sources
Purpose. 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.
How to use the result. Start with source data you can verify, enter values on a consistent unit and time basis, and record the assumptions used. The main inputs on this page include Fire Class, Occupancy Hazard Classification, Floor Area to Protect (sq ft), Your Name, Email, Company Name. Re-run the calculation when those assumptions change rather than carrying an old result forward.
Decision use. Use this tool for preliminary fire-risk or protection planning. Fire protection decisions should be confirmed against the applicable fire code, occupancy, material properties and site-specific emergency arrangements.
Limitations. Actual fire behaviour depends on ventilation, geometry, fuel distribution, ignition sources and protection-system performance; simplified results cannot represent every scenario.
Primary references. Use the current edition/version that applies to your jurisdiction and organization:
Editorial note. Prepared and maintained by Impact Tech Solutions. Editorially updated 28 September 2026. No individual professional credential is claimed on this page; high-consequence, statutory, tax, engineering or health decisions should be independently verified against the current primary source and, where required, a qualified professional.