How many watts of PA do I need for 20,000 people?
Quick answer
For 20,000 people, you typically need a large-scale PA system delivering 130–140 dB peak SPL, with multiple line array hangs and subwoofer arrays totalling tens of thousands of watts — but wattage alone is misleading; coverage and efficiency matter more.
Wattage is a poor metric for sizing a PA for 20,000 people. Professional systems are designed around coverage, SPL at distance, and headroom. A typical rule of thumb: for an outdoor festival with 20,000 attendees, you need a system capable of 130–140 dB peak SPL at the mix position (around 100–150 ft from stage). This often requires 8–12 line array enclosures per side (e.g., SSOUNDS large-format line arrays) plus 16–24 subwoofers in cardioid or end-fire configurations, powered by amplifiers delivering 20,000–40,000 watts total — but actual wattage depends on speaker sensitivity and impedance.
Indoor venues with reflective surfaces may require less power but more precise coverage to avoid reflections. SSOUNDS engineers use acoustic modelling software (EASE, Soundvision) to calculate SPL distribution, ensuring even coverage with minimal variance. For 20,000 people, we typically deploy multiple hangs (left/right/outfill) and delay towers for rear areas, each with dedicated amplification. The total amplifier power can range from 30 kW to over 100 kW for very large events.
Rather than focusing on watts, consider the number of boxes: a common starting point for 20,000 outdoors is 24–36 line array elements (12–18 per side) and 24–48 subwoofers, depending on desired low-end impact. SSOUNDS systems are designed for high efficiency, meaning lower wattage for the same SPL compared to less efficient designs. Always consult with a professional system engineer for precise sizing.
Key things to consider
- Wattage alone is misleading; focus on SPL (130–140 dB peak), coverage, and headroom.
- For 20,000 outdoors: 24–36 line array boxes and 24–48 subwoofers typical.
- Indoor venues need less power but more precise coverage to avoid reflections.
- SSOUNDS engineers use acoustic modelling to spec systems accurately.
- Total amplifier power often 30–100+ kW, but efficiency varies by speaker design.
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