Emergency Voice System Calculator

Speaker placement and wattage for fire alarm voice systems.

Floor area per story (sq ft)

Ceiling height (ft)

Ambient noise level (dBA)

Number of floors

Speaker type

Include strobes

Tab to move between fields

Total speakers

Speakers per floor2

Speaker spacing (ft)50

Required sound level (dBA)75

Total speaker wattage (W)150

Amplifier capacity (W)180

Amplifier units1

Total strobes9

NAC circuits3

How to Use This Calculator

Enter Floor area per story (sq ft), Ceiling height (ft), and Ambient noise level (dBA).
Set Number of floors, Speaker type, and Include strobes.
Review the Total speakers result.
Use Speakers per floor and Speaker spacing (ft) to inform your decision.

How the result changes with Floor area per story (sq ft)

Floor area per story (sq ft): Area of each floor to be covered by speakers and strobes.
Ceiling height (ft): Ceiling height affects speaker coverage and spacing.
Ambient noise level (dBA): Average ambient noise. Office=45-55, retail=55-65, industrial=70-85.
Number of floors: Total floors requiring voice alarm coverage.
Speaker type: 1=25W ceiling, 2=15W ceiling, 3=5W wall-mount.
Include strobes: 0=No, 1=Yes. Visible notification appliances (typically required by ADA/NFPA 72).

Total speakers: Total speaker/appliances needed across all floors.
Speakers per floor: Speakers required on each floor.
Speaker spacing (ft): Recommended center-to-center spacing.
Required sound level (dBA): Minimum sound level: 15 dB above ambient, at least 75 dBA.
Total speaker wattage (W): Total audio power required for all speakers.
Amplifier capacity (W): Required amplifier wattage with 20% headroom.
Amplifier units: Number of amplifier units needed.
Total strobes: Visible notification appliances (75 cd) across all floors.
NAC circuits: Notification Appliance Circuits required (2.5A per circuit).

Identify Input Parameters
4 parameters
Floor area per story (sq ft) = 5000, Ceiling height (ft) = 10, Ambient noise level (dBA) = 55, Number of floors = 3 = 6 input(s) provided
Calculate Total speakers
Total speakers
6 = 6
Calculate Speakers per floor
Speakers per floor
2 = 2
Calculate Speaker spacing
Speaker spacing
50 = 50