Decibel Addition Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the two source levels in dB.
- Read the combined level.
How it works
Combined = 10 × log₁₀(10^(dB1/10) + 10^(dB2/10)).
Worked example
80 dB + 80 dB. = 83 dB (not 160).
Common mistakes
- Adding decibels directly — they're logarithmic.
- Two equal sources add 3 dB; a source 10 dB quieter barely changes the total.
Frequently asked questions
Why do 80 + 80 dB make 83?
Doubling acoustic energy adds about 3 dB, not double the number — decibels are a log scale.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.