This tool converts a dB (deciBel) value to a voltage ratio.
Volt to dB Formula
V = 10PdB/20
Where
- V = Vout/Vin or the ratio between the output and input voltage
and
- PdB = 20*Log10(V)
Example Calculator
For a dB value of 3, the voltage ratio is 1.414.
Additional Notes
PdB represents a ratio between the output voltage from an amplifier to the voltage input to it. In other words it represents the power gain of the amp. It is a unit-less quantity. Many people confuse dB with dBm.
dBm is the dB value of power referenced to 1 mW. There is a voltage equivalent to both the input and output power in dBm (use this tool to convert from dBm to RMS voltage).
Let’s use an example where the Pout = 13 dBm and Pin = 10 dBm. In this case, PdB = 13-10 = 3 dB (using the dBm to dB calculator).
- 13 dBm = 1 Volt (Vout)
- 10 dBm = 0.707 Volt (Vin)
- Vout/Vin = 1.414 which is the same result in this calculator