In this post we have two Watt to dB calculators. The first one is applicable for radio communications. The second one is for audio systems.
Convert Watt to dB for RF systems
dB or decibel is a relative number. Watt is an absolute number. It’s not possible to convert between Watt and decibel or dB.
However it is possible to calculate dBm from Watt and vice versa.
This calculator lets you convert from Watt to dBm
This calculator lets you convert from dBm to Watt
Convert Watt to dB for Audio Systems
This next calculator is used to convert from Watt to dB as a measure of sound or noise level.
Sound power levels or LwdB are determined by the following formula:
LwdB = 10*Log10 (Lw/ LR)
The reference power LR is one trillionth of a Watt or 10-12 W
LW is the power specified in Watt
Use the tool below to convert from Watt to dB
The picture below shows the sound power level in dB vs the sound power level in Watt (W)

Use this calculator to convert from dB to Watt
If you are looking for calculators that are specific to Electronics and Electrical Engineering, please see the list below. In all of these cases dB is a relative quantity and as such dimensionless.
dBm however is dB referenced to 1 mW. Similarly dBW is dB referenced to 1 W.