Calculating the CiteScore is based on the number of citations to documents (articles, reviews, conference papers, book chapters, and data papers) by a journal over four years, divided by the number of the same document types indexed in Scopus and published in those same four years.
For example, the 2023 CiteScore counts the citations received in 2020-2023 to articles, reviews, conference papers, book chapters, and data papers published in 2020-2023, and divides this by the number of these documents published in 2020-2023.
Four-year window
Peer reviewed bibliometric literature, such as the Journal of Information Science, shows that a three-year window is long enough to capture the citation peak for the majority of disciplines. However, a four-year window was chosen to allow for a more recent year to be included in the equation, making the calculation more robust and stable. CiteScore uses a 4-year window.