This tool converts from linear value to dB (deciBel).
PdB = 10*Log10(Plinear)
Plinear = 10(PdB/10)
The dB scale is a convenient way to represent both large and small numbers. For instance, 10000000000 = 100 dB while 0.0000000001 = -100 dB.
Neither the linear value nor the dB value have units. If a number A is 100 times greater than another number B, then on the log scale we can say that A is 10*Log10(100) = 20 dB greater than B.
Let’s say an amplifier module amplifies the input signal power by a factor of 10,000. Using the calculator, we can say that it is a 40 dB amplifier. The gain of an RF amplifier is almost always specified in terms of dB.