Gain

In electronics, gain is the ratio of signal output from a system to signal input to the system. A signal is usually measured in units of power, since a power gain is considered more meaningful than a voltage gain.

The ratio is often expressed in decibels (dB).

For example, if output=500mW and input=5mW then

gain=500/5 = 100 = 2B (bel) or 20dB

---

In finance, gain is profit or increase in value of an investment such as stock and bond. Gain is calculated by fair market value or proceed from sale of the investment minus the sum of purchase price and all costs associated with it. If the investment is not converted into cash or another asset the gain is called unrealized gain.

---

In psychology, primary gain and secondary gain are commonly seen in Somatoform Disorders.