Decibel ↔ ratio converter
Convert decibels to voltage/pressure ratios, power ratios and nepers, and back.
dB
×
×
Np
How it works
Voltage and sound pressure are 'field' quantities, so a ratio is 20·log₁₀. Power and intensity are 'power' quantities, so it is 10·log₁₀. That is why +6 dB doubles voltage but needs +3 dB to double power.
Ratios must be greater than zero; a ratio of zero would be −∞ dB.
Formulas
- dB = 20 · log₁₀(V₂ / V₁)
- dB = 10 · log₁₀(P₂ / P₁)
- 1 Np = 20 / ln 10 dB ≈ 8.686 dB
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