Smoke Detector Spacing Calculator
Calculate smoke detector grid layout and spacing for different ceiling types per NFPA 72.
Inputs
Results
Detectors Needed
2
Adjusted Spacing (ft)
30
Coverage per Detector (sq ft)900
Detectors Along Length2
Detectors Along Width1
Room Area (sq ft)1,200
Max Wall Offset (ft)15
How to Use This Calculator
- Enter Room Length (ft), Room Width (ft), and Ceiling Height (ft).
- Set Ceiling Type.
- Review Detectors Needed and Adjusted Spacing (ft).
- Use Coverage per Detector (sq ft) and Detectors Along Length to inform your decision.
How the result changes with Room Width (ft)
| Room Width (ft) | Detectors Needed | Adjusted Spacing (ft) |
|---|---|---|
| 55 | 4 | 30 |
| 178 | 12 | 30 |
| 327 | 22 | 30 |
| 451 | 32 | 30 |
What each input means
- Room Length (ft)
- Length of the room in feet.
- Room Width (ft)
- Width of the room in feet.
- Ceiling Height (ft)
- Floor-to-ceiling height in feet.
- Ceiling Type
- 1=Flat/Smooth, 2=Beamed, 3=Sloped, 4=Peaked.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersRoom Length (ft) = 40, Room Width (ft) = 30, Ceiling Height (ft) = 10, Ceiling Type = 1 = 4 input(s) provided
- Calculate Detectors NeededDetectors Needed2 = 2
- Calculate Adjusted SpacingAdjusted Spacing30 = 30
- Calculate Coverage per DetectorCoverage per Detector900 = 900
- Calculate Detectors Along LengthDetectors Along Length2 = 2
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