dBm is a type of decibel measurement, referenced to one milliwatt (mW). Measurements in dBm can be converted to and from Watts, but not voltage or current without knowledge of the load impedance (see Ohm's Law).
To convert a value x, in Watts, to a value, y, in dBm:
y = 10 * log_10(x / 0.001)
To convert a value y, in dBm, to a value x, in Watts:
x = 0.001 * 10^(y / 10)
To convert a value x, in Watts, to a value, y, in dBm:
y = 10 * log_10(x / 0.001)
To convert a value y, in dBm, to a value x, in Watts:
x = 0.001 * 10^(y / 10)
