How many watts do I need per person?

As a rough guide: speech = 1-2 W/person, acoustic music = 3-5 W/person, full band = 5-10 W/person, DJ/dance = 10-15 W/person. Outdoor events need 2-3x more power than indoor because there are no reflective surfaces to help.

Do I always need subwoofers?

For speech-only events, subs are unnecessary. For acoustic music, they add warmth but are optional. For full band, DJ or dance music, subs are essential for the low-end impact below 100 Hz that tops cannot reproduce effectively.

What is headroom and why does it matter?

Headroom is the extra power available above your normal operating level. 6 dB of headroom means your system can handle peaks at 4x the average power without clipping. This prevents distortion on transients and protects speakers from damage.

When do I need delay speakers?

Delay speakers (also called fills) are needed when the main PA cannot cover the full venue depth with consistent SPL. Typically when the throw distance exceeds 20-25 m. They are time-aligned to the main PA to maintain coherent sound.

AudioCalcs

PA Speaker Calculator \u2014 System Sizing for Venues

Calculate PA system requirements based on venue size, audience and music type.

Venue Size

Size specification

Venue Type

Select the type to use

Audience Size

Size specification

Music Type

Select the type to use

Coverage Angle Needed

Total horizontal coverage

How We Calculate This

Required power = 10^((target SPL - sensitivity + distance loss) / 10)

Speaker sensitivity is typically 96 dB at 1 W/1 m. Sound level drops 6 dB per doubling of distance (inverse square law).

Delay timing = (distance to delay speaker / 343 m/s) × 1000

Outdoor venues require 2-3× more power than indoor due to lack of reflected sound energy.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.