Plan extinguisher placement using practical engineering inputs today. Pick hazard level and extinguisher rating options. Get clear counts, spacing, and downloadable reports in seconds.
This calculator uses three independent checks and selects the maximum:
| Scenario | Area (m²) | Hazard | Risk | Floors | Suggested count |
|---|---|---|---|---|---|
| Small office | 450 | Light | A | 1 | 1–2 |
| Retail floor | 1,200 | Ordinary | A | 1 | 3–5 |
| Workshop | 900 | Extra | A | 1 | 4–7 |
| Paint room | 150 | Ordinary | B | 1 | 2–4 |
| Mixed plant | 2,500 | Extra | M | 2 | 10–16 |
Accurate coverage starts with protected floor area, floor count, and the hazard classification. This calculator converts m² to ft² internally (1 m² = 10.7639 ft²) so mixed unit inputs remain consistent. Light-hazard spaces typically allow larger coverage per A-unit than extra-hazard areas. If your project includes mezzanines or separated compartments, treat them as independent zones and sum results for a conservative total. Document room uses, storage height, and combustibility to justify selection.
Class A sizing uses the extinguisher A rating as “A-units.” The calculator multiplies A-units by a default base coverage per unit: 3,000 ft² for light hazard, 1,500 ft² for ordinary hazard, and 1,000 ft² for extra hazard. You may override this base to match an internal standard. A safety margin reduces effective coverage using effective = coverage ÷ (1 + margin). Higher margins increase recommended quantity for resilience and accessibility during operations.
The spacing check models reach using a circular influence area: π × travel_distance². Real buildings are not circles, so the tool applies a layout efficiency factor between 0.35 and 0.85 to represent corridors, obstructions, and overlap. A lower factor is appropriate for dense equipment rooms; a higher factor fits open halls. Enable this check when travel limits drive placement, then compare its count to the area-based result to see which constraint governs.
For Class B risks, the calculator estimates quantity from flammable-liquid surface area. It treats the selected B rating as an approximate ft² fire size and divides your liquid surface area by effectiveB = B_units ÷ (1 + margin). Because fuel type, depth, and containment change severity, use this only as a preliminary check. Enter the spill area near pumps, mixing stations, or dip tanks. Add units at points of transfer and ignition.
The final recommendation is the maximum of enabled constraints: area coverage, liquid surface estimate, spacing check, and any minimum-per-floor rule. This aligns with conservative engineering practice: design to the controlling criterion. Use the “per floor” value to allocate stock, then refine placement with a walk-through and marked egress paths. Keep a mix of agent types matched to hazards, and record the final locations for inspection programs and training. Revisit inputs after changes.
Select ratings that match your standard equipment list. Higher A or B ratings increase estimated coverage per unit and can reduce quantity, but may affect weight, bracket choice, and cost. Verify availability and compliance with your local authority.
Many rating references and common planning rules use square feet. Converting everything to ft² avoids mixed-unit errors, then the calculator also reports m² for convenience. The conversion used is 1 m² = 10.7639 ft².
Safety margin reduces effective coverage to reflect uncertainty, blocked access, and future layout changes. A 10% margin divides coverage by 1.10, increasing the recommended count. Use higher margins for complex layouts or higher consequence areas.
Enable it when a maximum travel distance is a project requirement or when corridors and partitions strongly influence reach. It estimates coverage using a circular area adjusted by layout efficiency. If disabled, results rely mainly on area and hazard assumptions.
Enter the expected flammable-liquid surface area for the largest credible spill or process area you want to cover. The tool compares that area to the selected B rating as a simplified check. Use this alongside code guidance for final placement.
No. It produces planning estimates and helps you explore “what-if” scenarios quickly. Final designs must consider egress routes, equipment types, special hazards, and local enforcement requirements. Always confirm with a qualified professional and the authority having jurisdiction.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.