Watt to dB Calculator

This tool converts from Watt to dB as a measure of Sound or Noise Level.

Enter the power level in Watt.



???? dB to Watt


Sound power levels or LwdB are determined by the following formula:

LwdB = 10*Log10 (Lw/ LR)


  • The reference power LR is one trillionth of a Watt or 10-12 W
  • LW is the power specified in Watt

Example Calculation

The Saturn V rocket has a Sound Power level of 100,000,000 Watt. This is equivalent to 200 dB (dangerously high levels!).

A quiet conversation (at the opposite end of the audio scale) has a level of 10−9 W = 0.000000001 Watt. This is equivalent to 30 dB.


Sound Power Level (abbreviated as SWL) is the rate at which sound energy is emitted, reflected, transmitted or received. It does not depend on distance from the source.

Contrast this with Sound Pressure Level (SPL) which has a distance associated with it and usually specified in audio systems like speakers, sub woofers and amplifiers.

Even though they are different, the above calculator can be used to convert from Watt to dB.

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