🔊 Distance Attenuation Calculator
Enter a known sound or light level at a reference distance, then a new distance, to calculate the attenuated level using the inverse square law.
What is distance attenuation?
Sound and light intensity drop off rapidly with distance from a point source, because the same total energy spreads out over an ever-expanding sphere as it travels outward.
The formula
The inverse square law states that intensity is proportional to 1 ÷ distance2. In decibel terms this becomes L2 = L1 − 20log10(d2 ÷ d1), meaning every doubling of distance reduces level by about 6 dB.
This formula assumes a point source radiating freely in open space (free-field conditions), with no reflections, absorption, or directional focusing; real environments like rooms or outdoor terrain can deviate from this ideal. This calculator is for general acoustics and physics education.