Decibel Adder: Why Two Sounds Do Not Double the Decibels
Decibels are logarithmic, so adding them needs a formula, not simple addition. This tool does that maths for two sources.
What is the Decibel Adder?
Decibels do not add like ordinary numbers: two equal sources raise the level by only about 3 dB. Enter two levels and this tool combines them with the proper logarithmic formula.
How to use it
- Enter your values in the fields provided.
- Click Add Decibels.
- Read the result and adjust an input if you want a different outcome.
Worked example
Two 80 dB sources together give about 83.01 dB, not 160 dB.
What do two 80 dB sources add up to?
The logarithmic sum is 10 times log base 10 of twice 10 to the power 8, which is about 83.01 dB.
Frequently asked questions
What do I enter to get a result?
Fill in every field with your own numbers or choices, then run the tool. Empty number fields count as zero, so check them before you trust the output.
Can I reuse this result elsewhere?
Yes. The result is calculated in your browser from the values you entered, so you can copy the numbers into your own notes or plan.