Decibel (dB) Converter
Convert between gain in decibels and voltage or power ratio, and find an output voltage from an input and a gain.
Gain–
Voltage ratio–
Power ratio–
Output voltage (from Vin)–
Decibels, voltage and power
Gain (dB) = 20 · log₁₀(Vout / Vin) = 10 · log₁₀(Pout / Pin)
Voltage ratio = 10^(dB / 20) · Power ratio = 10^(dB / 10)
A decibel is a logarithmic ratio. Because power is proportional to voltage squared, the same gain in dB corresponds to a voltage ratio and a power ratio that is its square. Handy landmarks: +6 dB ≈ ×2 voltage(×4 power), +20 dB = ×10 voltage (×100 power), and−3 dB ≈ ×0.707 voltage (half power — the filter cutoff point).
A negative dB value is attenuation (ratio below 1); zero dB means the output equals the input.