To calculate fiber loss, the easiest and most accurate way is to perform an Optical Time Domain Relectometer (OTDR) trace of the actual link. This will give you the actual loss values for all events (connectors, splices and fiber loss) in the link. Sometimes the power budget has both a minimum and maximum value, which means it needs at least a minimum value of loss so that it does not. Use this worksheet to input values for all variables that will impact your system's performance. This step is necessary to see if your system falls within. This page provides information about a Fiber Optic Loss calculator and the formulas used in its calculations.