Decibel Addition Calculator
Fill in the value and the answer updates as you type.
How the Decibel Addition Calculator works
Decibels are logarithmic, so they cannot be added directly. Total level = 10 × log₁₀(sum of 10^(level ÷ 10)). Two equal sources add 3 dB, four add 6 dB, and ten add 10 dB. A source 10 dB quieter than the loudest one adds only about 0.4 dB. This assumes the sources are uncorrelated. Example: with Sound levels, separated by commas 80, 80, 75 dB, the result is Combined level (dB) = 83.6; Increase over the loudest source (dB) = 3.6; Loudest single source (dB) = 80.
Inputs and results
The Decibel Addition Calculator takes 1 input and gives 4 results.
What you enter
- Sound levels, separated by commas (dB) — starts at 80, 80, 75.
What you get
- Combined level (dB)
- Increase over the loudest source (dB)
- Loudest single source (dB)
- Number of sources
Example: Decibel Addition Calculator with the starting values
With sound levels, separated by commas 80, 80, 75 dB, the calculator returns:
| Combined level (dB) | 83.6 |
|---|---|
| Increase over the loudest source (dB) | 3.6 |
| Loudest single source (dB) | 80 |
| Number of sources | 3 |
Change any value above and the results update straight away.
Decibel Addition Calculator FAQ
How do I use the Decibel Addition Calculator?
Enter sound levels, separated by commas in the fields, then read combined level (db), increase over the loudest source (db), loudest single source (db) and number of sources in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Decibel Addition Calculator calculate?
Combine several sound sources into one total dB level. It returns combined level (db), increase over the loudest source (db), loudest single source (db) and number of sources from the 1 value you provide.
What values does the Decibel Addition Calculator start with?
It opens with sound levels, separated by commas 80, 80, 75 dB so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Decibel Addition Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Decibel Addition Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.