The ability to measure strains quasi-continuously with high spatial resolutionmakes distributed fiber optic sensing a promising technology for structuralhealth monitoring as it allows to locate and measure damages in concretestructures, such as cracks. Depending on whether the distributed fiber opticsensor (DFOS) is embedded into the concrete matrix or bonded to the rein-forcement, different approaches for crack width calculation exist. The high spa-tial resolution of DFOS quickly leads to a large amount of data, especially withtime continuous monitoring. Scalable, automated analysis approaches arerequired to handle such big data and to derive a gain in knowledge from themeasurements. Thus, in a first step, the PYTHON framework fosanalysis ispresented and made available to other researchers or monitoring specialists asfree software. The most important input parameters for crack width calculationare discussed for concrete strain and steel strain DFOS. Accurate crack moni-toring for a 4 m long reinforced concrete beam is demonstrated by using fosanalysis. The calculated crack widths are in good agreement with digi-tal image correlation measurements.