Fiber optic loss calculation formula: Total link loss (LL) = Cable attenuation + Connector attenuation + Fusion attenuation [Note: If there are other components (such as attenuators), their attenuation values can be added]. This page provides information about a Fiber Optic Loss calculator and the formulas used in its calculations. This calculator determines fiber loss based on input power, output power, and the length of the fiber optic cable. Example Calculator #1: The following formula is used for Calculator #1:. Fiber optic loss, also known as optical attenuation, refers to the light loss between the transmitter and receiver. Sometimes the power budget has both a minimum and. After measuring the loss of a fiber link, you now have to determine if that fiber link loss is acceptable or not.