Decibel addition calculator
Type the source levels separated by commas or lines to get their combined level. Two 60 dB sources give about 63 dB, not 120 dB.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter sound levels in db.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
L total = 10 × log₁₀(Σ 10^(Lᵢ / 10)); energy average = 10 × log₁₀((Σ 10^(Lᵢ / 10)) / n).
Example
Result: Total level: 67.89 dB; Energy average: 63.12 dB; Number of sources: 3.
Limits and caveats
- It assumes incoherent sources such as machines and engines. Two identical in-phase tones can add up to 6 dB instead of 3 dB.
Questions about this tool
Why not just add the decibels?
Decibels are logarithmic, so each level is turned into energy, the energies are summed and the total is turned back into dB.
How much louder is it with twice the sources?
Doubling the number of equal sources adds about 3 dB.
What if one source is much louder?
When the gap is over 10 dB, the quieter source adds less than half a decibel to the total.