Fiber optic loss, also known as optical attenuation, refers to the reduction of optical signal power as light propagates through an optical fiber link. Loss is expressed in decibels (dB) and accumulates across all elements of the optical path. In real-world deployments, fiber optic loss directly constrains transmission distance, split ratio, network. To be able to judge whether a fiber optic cable plant is good, one does a insertion loss test with a light source and power meter and compares that to an estimate of what is a reasonable loss for that cable plant. Contractors often install, terminate, and certify cabling without knowing the client's specific requirements. After entering your values, please ensure you click the 'Calculate Link Loss' button at the bottom of the page to generate your total link loss. This step is necessary to see if your system falls within. Put simply, insertion loss (IL) is the measurement of light that is lost between two fixed points in the fiber.