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Inverse-Square Law Intensity Calculator

I₂ = I₁ · (r₁ / r₂)² for a point-source field.

Apply the inverse-square law to a point-source intensity (light, sound, gravity, radiation) — given the intensity at one distance, compute the intensity at any second distance, and report the dB drop.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

I₂ = I₁ · (r₁ / r₂)²; ΔdB = 20 · log₁₀(r₂ / r₁).

In depth

Apply the inverse-square law to a point-source intensity (light, sound, gravity, radiation) — given the intensity at one distance, compute the intensity at any second distance, and report the dB drop.