This document specifies the determination of the size weighted fine fraction (SWFF) and the size weighted fine fraction of crystalline silica (SWFFCS) in bulk materials by calculation. The document also describes the assumptions and preconditions to be fulfilled in order for this method to be valid. The purpose of this document is to allow users to evaluate bulk materials with regard to their size-weighted fine fraction and crystalline silica content. The calculation method is applicable only after experiments have shown that the results are accurate and consistently equal or higher than the results from sedimentation, as described in prEN 17289-3:2018, for that particular bulk material. For preparation of the sample and determination of crystalline silica by XRD and FT-IR see prEN 17289-1:2018. A specific method for the evaluation of the SWFF for diatomaceous earth bulk materials is given in Annex A. Due to the internal porosity of diatomaceous earth, the general instructions given in this document are adapted in order to take into account the material s effective density. This document is applicable for bulk materials which have been fully investigated and validated. The criteria for the materials are described in this document and prEN 17289-3:2018. This includes industrial minerals which can contain crystalline silica such as quartz, clay, kaolin, talc, feldspar, mica, cristobalite, vermiculite, diatomaceous earth, barite, andalusite, iron ore, chromite etc.