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Decibel Calculator

Add decibel levels, convert between power/amplitude ratios and dB, and compare two sound levels.

Enter values

Results update as you type.

Result

Combined level

86.76 dB

Two equal sources add only 3 dB — not double the number.

Increase over the louder source
1.76 dB

About the Decibel Calculator

Add decibel levels, convert between power/amplitude ratios and dB, and compare two sound levels.

Also known as: db calculator, add decibels, db difference, sound comparison.

How to use this calculator

  1. Enter calculate, level 1.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

L_total = 10·log₁₀(10^(L₁/10) + 10^(L₂/10))

Worked example

Using the values pre-filled in the calculator above:

  • Calculate: Add two sound levels
  • Level 1 = 85 dB
  • Level 2 = 82 dB

the calculator returns:

  • Combined level: 86.76 dB
  • Increase over the louder source: 1.76 dB