Decibels use a logarithmic scale because human hearing spans a huge range of intensities.
How to use the Decibel Calculator
- Sound level 1
- Sound level 2
Results update as you type, and every field accepts the units shown in its menu.
How it works
Sound levels add as intensities, so they are converted out of decibels, summed and converted back.
Inputs explained
| Field | What to enter |
|---|---|
| Sound level 1 | In dB |
| Sound level 2 | In dB |
What each result means
- Combined level = 10×log10(10^([Sound level 1]÷10) + 10^([Sound level 2]÷10))
- Pressure of level 1 = 20e-6 × 10^([Sound level 1]÷20)
- Intensity ratio (1 vs 2) = 10^(([Sound level 1] – [Sound level 2])÷10)
Example values
How the main result changes when Sound level 1 changes and everything else stays at the example values above:
| Sound level 1 (dB) | Combined level (dB) |
|---|---|
| 40 | 80 |
| 60 | 80.04 |
| 80 | 83.01 |
| 100 | 100.04 |
| 120 | 120 |
| 160 | 160 |
Formula
L = 20 log₁₀(p ÷ 20 µPa)Combined = 10 log₁₀(10^(L₁/10) + 10^(L₂/10))Worked example
Inputs — Sound level 1: 80 dB; Sound level 2: 80 dB.
Results — Combined level = 83.01 dB; Pressure of level 1 = 0.2 Pa; Intensity ratio (1 vs 2) = 1 ×.
Frequently asked questions
Is 80 dB twice as loud as 70 dB?
It has ten times the intensity and sounds roughly twice as loud.
At what level does hearing damage start?
Prolonged exposure above about 85 dB can damage hearing.
What formula does the Decibel Calculator use?
L = 20 log₁₀(p ÷ 20 µPa).