Sound Level Addition Calculator

This tool computes the sum of any number of audio sound levels (dB).

Enter the sound levels in dB, each separated by a comma.


LTotal = 10*Log10[10L1/10 + 10L2/10 + 10L3/10 … + 10LN/10]


  • L1, L2, … LN are the dB sound levels of the sources
  • LTotal is the total combined sound level in dB

Example Calculation

The combined sound level from three sources with levels 5 dB, 10 dB and 15 dB is 16.5 dB. This is equivalent to 4.5e-11 Watt.

For a practical example let’s imagine there are three different audio sources: A refrigerator, two people speaking softly and a vacuum cleaner.

The table below provides the sound power levels associated with each

Audio SourceSound Level (dB)
People speaking softly30
Vacuum cleaner70
Combined Sound Level 70.0048

The last row provides the sum (in dB) of the three sources ~70 dB. Essentially, the vacuum cleaner noise will drown out the other two as expected.

Note that sound power level (unlike sound pressure level) does not depend on distance.


The total sound level is the Log of the linear sum of powers in Watt. The calculator above converts each dB value to a linear equivalent 10L/10. (This is similar to converting a dB value to power ratio).

The next step is to convert back to Log. In other words calculate 10*Log10(Linear sum of powers).

A sound level meter like the one shown below does exactly this in the real world.

REED Instruments R8060 Sound Level Meter with Bargraph

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