How this calculator works
The Coverage Angle Calculator estimates how wide one speaker or a simple horizontal speaker group spreads at a given throw distance and what on-axis level you might expect from sensitivity and amplifier power. It is aimed at live sound engineers, installers, and system designers who need quick coverage width and SPL checks before splaying cabinets or choosing horn patterns.
Coverage width uses the included angle between the -6 dB points. On-axis SPL applies the inverse-distance relationship from sensitivity at 1 W / 1 m. Real venues add reflections, absorption, and pattern irregularity, so treat results as planning estimates—not measured prediction.
Formula used
Coverage width: width = 2 × distance × tan(angle / 2)
Multi-speaker fan angle: total angle = speaker angle + (speaker count − 1) × speaker angle × (1 − overlap fraction)
On-axis SPL (estimate): SPL ≈ sensitivity + 10×log₁₀(power) − 20×log₁₀(distance)
Example calculation
With a 90° horizontal coverage angle, two speakers, 15% overlap, 20 m throw, 98 dB sensitivity, and 500 W per speaker: adjacent axes are 76.5° apart, the total fan angle is 166.5°, and each speaker covers about 40 m at that distance. On-axis SPL for one cabinet is about 99 dB before air losses and array interaction.
Key terms
- Coverage angle — included angle between -6 dB points off the acoustic axis.
- Overlap — how much of one speaker's nominal coverage angle is shared with the adjacent speaker.
- Throw distance — horizontal distance from the source to the audience plane.
- Sensitivity — SPL at 1 W into 1 m on axis, in dB.
- Splay / overlap — aiming adjacent cabinets so coverage overlaps roughly 10–20% for even level.
Frequently asked questions
- What is speaker coverage angle? The included angle between the -6 dB points off axis; it describes how wide the main beam spreads at a reference level.
- How do you calculate coverage width from angle and distance? Use width = 2 × distance × tan(half-angle). Enter the full included angle; the calculator uses half of it internally.
- Is horizontal coverage the same as vertical coverage? No. Many PA boxes have different horizontal and vertical patterns; this tool uses one angle you enter—match it to the plane you are planning.
- Why does real-world speaker coverage differ from the calculation? Horn ripple, cabinet interaction, air absorption, and room reflections change level and width. Measure on site when alignment is critical.