This tool converts a **dB** (deciBel) value to a voltage ratio.

**Formula**

**V = 10 ^{PdB/20}**

Where

**V = Vout/Vin**or the ratio between the output and input voltage

and

**PdB = 20*Log**_{10}(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