Decibel (dB) Calculator

Decibels are defined as ten times the log of a power ratio or twenty times the log of Voltage Ratio. dB = 20log10(V1/V2) = 10log10(P1/P2)

Input

Enter either Power Gain (P1/P2) or Voltage gain to calculate the Decibel (dB).

Power Gain (P1/P2): (OR) Voltage Gain (V1/V2):

Output

Decibels (dB):

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You can also use this calculator to find out the Power Gain and Voltage Gain from the Decibel value. Just enter the Decibel value and leave Power Gain & Voltage Gain blank, and then hit the Calculate button.

dBm Calculator:

As we know Decibel in dB can be calculated as: dB= 20log(V1/V2)= 10log(P1/P2) If we put P2 = 1mW = .001 watt  then it becomes dBm: dBm= 10log(p1/.001) Means dBm is calculated when the input power is considered as 1mW 

Power (P) (Watts): dBm: