Soma dois níveis dB
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The dB level addition calculator combines two decibel (dB) measurements, which are logarithmic units. Direct addition of dB values is incorrect because dB represents sound power. The formula used is 10·log(10^(a/10) + 10^(b/10)), converting dB to linear scale, summing power levels, and returning to logarithmic scale. This is critical in acoustics, audio engineering, and noise analysis.
This tool applies when multiple sound sources act simultaneously, such as in factory machinery noise assessments or studio signal mixing. For example, combining 80 dB and 83 dB from two independent sources results in approximately 84 dB, not 163 dB. The calculator prevents linear interpretation errors.
Note: The formula requires independent sources at the same location and frequency. For more than two sources, repeat the calculation iteratively. Negative values or missing data should not be used here. Always verify environmental conditions before applying results to technical analyses.
Frequently asked questions
Why can't I just add dB values directly?
Decibels are logarithmic, not linear. Direct addition underestimates sound perception. The formula converts dB to power, sums, and returns to correct scale.
How does the formula 10·log(10^(a/10)+10^(b/10)) work?
It converts each dB to power (10^(x/10)), sums power values, then applies logarithm to return dB scale. E.g., 80 dB + 80 dB = 83 dB.
When to use this calculator?
To sum noise levels from independent sources like motorcycles, appliances, or industrial machinery.
Can the result exceed 100 dB?
Yes, but increases follow logarithmic law. E.g., 100 dB + 100 dB = 103 dB, not 200 dB.