Audio Tools

Decibel Ratio Calculator

Convert between decibels and a plain amplitude or power ratio, in either direction.

6.021 dB

Amplitude ratios use dB = 20·log₁₀(ratio) (for voltage/pressure-like quantities); power ratios use dB = 10·log₁₀(ratio) — pick the type that matches what your ratio measures.

How to use this tool

  1. 1Choose the conversion direction.
  2. 2Choose whether your ratio is an amplitude (voltage) or power ratio.
  3. 3Enter the known value.
  4. 4See the converted result.

Frequently asked questions

Why do amplitude and power ratios use different formulas?+

Power is proportional to the square of amplitude, so an amplitude ratio needs a factor of 20 in the dB formula (20·log₁₀) where a power ratio only needs a factor of 10 (10·log₁₀) to give the same dB value for the same underlying change.

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