Insertion Loss in Decibels
Insertion loss quantifies how much signal power a component (a cable, connector, filter, or splitter) removes from a transmission line, expressed logarithmically: IL (dB) = 10 × log10(Pin / Pout), where Pin and Pout are the power measured before and after the component.
A larger insertion loss value means more signal is lost. Because decibels are logarithmic, a 3 dB loss corresponds to losing about half the power, while a 10 dB loss means losing 90% of the power. This metric is standard in RF, fiber-optic, and audio system design for characterizing passive component performance.
Last reviewed August 2026