Decibel Calculator (Power & Amplitude)
Convert power or amplitude ratios to decibels.
Step-by-step working
- L = 10 log₁₀(P/P₀) = 10 log₁₀(100/1)
- = 20 dB
Mathematical Formula
Overview & Explanation
Decibels express ratios on a log scale; amplitude ratios use 20 because power ∝ amplitude².
How It Works
- Pick power or amplitude.
- Divide by reference.
- Take the log.
Practical Applications
- Audio gain.
- RF link budgets.
Example 1: power ratio 100
20 dB.
Inputs
Quantity: Power / intensity (10 log) · Measured value: 100 · Reference value: 1
Step 1
L = 10 log₁₀(P/P₀) = 10 log₁₀(100/1)
Step 2
= 20 dB
Level
Result
Example 2: voltage ratio 2
≈ 6.02 dB.
Inputs
Quantity: Voltage / pressure amplitude (20 log) · Measured value: 2 · Reference value: 1
Step 1
L = 20 log₁₀(A/A₀) = 20 log₁₀(2/1)
Step 2
= 6.021 dB
Level
Result
How it's calculated & sources
Power: L = 10 log₁₀(P/P₀). Amplitude: L = 20 log₁₀(A/A₀).
Frequently Asked Questions
Why 3 dB = double power?
dB SPL?
Negative dB?
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