Studio Matrx Monthly · Volume 1 · Issue 2 · July 2026
Amogh N P
 In loving memory of Amogh N P — Architect · Designer · Visionary 
Fire detection

Smoke Detector Quantity Calculator

Two things set the count: the floor area each detector can watch on a flat ceiling, and the discrete spaces — every enclosed room and stair landing needs its own coverage. Enter both and the greater number governs. This is an indicative planning estimate; it runs in your browser and nothing is stored.

Mount detectors on the ceiling, more than 0.5 m from any wall and away from AC vents; in a pitched roof, fix within about 0.9 m of the apex. Use heat detectors, not smoke, in kitchens and garages to avoid nuisance alarms — and always cover every escape route.
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Smoke detectors (indicative)
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From area
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Rooms + stairs
Governed by
Discrete rooms & stairs
the enclosed spaces need more detectors than the raw area

Indicative planning estimate only — this is not a compliant fire design or a statutory calculation. The actual requirement depends on the occupancy classification, building height and the AHJ. Detector coverage drops with ceiling height, beams and obstructions. A licensed fire consultant must design the detection system to the NBC (SP 7:2026) / IS 2189, and the local fire officer / AHJ signs it off. A wrong number here can cost lives — verify everything.