This tool converts from deciBel to a Percentage.
ALinear = 10AdB/10
A% = 100*ALinear
3 dB is a commonly used quantity in the world of RF engineering.
A two port device called a 3 dB splitter (as the name suggests) splits the input power in two. In actual fact, it is -3 dB. This is a linear value of 0.5 and in fact half the power appears on each output port. In percentage terms, the value is 50%. Essentially it is a halving of value.
A 10 dB amplifier results in an output power that is ten times the input power. In percentage terms this is 1000%.