Electrical and Electronic Equipment (EEE) is valued for its usability, generating an important waste stream, but overall information on their flows through society is generally not available. Data on End-of-Life (EoL) flows is scattered, unstructured, with varying classifications and formats, and uncertain levels of data quality and availability. This provides a big challenge of a structured mapping of the Waste Electrical and Electronic Equipment (WEEE) flows, both officially reported as collected and complementary flows (the term refers to all flows not documented at a national level via designated official compliance schemes). To address these issues, a model quantitatively describing the WEEE flows has been developed based on the Commission Implementing Regulation (EU) 2017/699 and WEEE Directive collection targets. Consequently, it evaluates the impacts of WEEE Directive policies that have been adopted in the past. The model is applied to the EU Member States, as well as Great Britain, Norway, and Switzerland, for the reference year of 2018. The results show that about 9.7 Mt of WEEE was generated, whereas roughly 5.0 Mt were collected. The analysis shows that a significant amount of waste (4.7 Mt) was not properly collected and recycled. Of the total amount of complementary flows, the majority, approx. 1.1 Mt was in complementary recycling (mixed metal scrap). Moreover, the obtained results provide an insight to improve collection targets through multidimensional drivers, i.e., economic policies, legal framework, and sustainability approach that are needed to be set in waste management.