Sound Distance Falloff Calculator

About this calculator

Sound intensity follows the inverse-square law: as sound waves spread out spherically from a point source, their energy is distributed over an ever-larger area, so intensity falls off with the square of distance. In terms of sound pressure level, this works out to a drop of 6 dB every time the distance from the source doubles — a rule of thumb well known to anyone who has stepped back from a loudspeaker.

This calculator applies the formula L2 = L1 − 20·log10(d2/d1) to find the sound pressure level at a new distance given a known reference level. It's an everyday tool for audio engineers and live sound technicians setting speaker levels and predicting coverage, as well as for noise assessment and architectural acoustics work, where estimating how loud a source will be at a given distance matters for hearing-safety and community-noise compliance.