# Current gain - simplified formula (for equal impedances)

## Description

The current gain can be calculated using current instead of power using Joule’s first law to calculate. In many cases, the input and output impedances are equal.

This simplified formula, the 20 log rule, is used to calculate a current gain in decibels and is equivalent to a power gain only if the impedances at input and output are equal.

Related formulas## Variables

gain_{dB} | Current gain (dB) (dimensionless) |

I_{out} | Output current (dimensionless) |

I_{in} | Input current (dimensionless) |