The Decibel

By definition, the ratio expressed as a dB value is simply 10 times the LOG.

Gain (dB)   =   10  x  LOG(POUT/PIN)

For estimating and verifying your calculations, here is a useful table of values that you will want to memorize :
POUT/PIN dB
1 0
10 10
100 20
1000 30
etcetera
For estimating, add this close approximation to your repertoire :
POUT/PIN dB
2 3



In working with PW (pulse width) we used the term '1/2-power points'.
Each factor of 2 corresponds to 3dB, so the term '3dB-points' is also used.