The impact factor (IF) is a commonly used means to measure the importance (or rank) of a scholarly journal. The IF measures the frequency an article from a given journal has been cited in a year. A journal’s impact factor is calculated using a two-year period by dividing the number of times articles from that journal were cited by the number of articles from that journal that could have been cited.
So the 2020 IF for a journal is based upon the number of articles published in 2018 and 2019 which were then subsequently cited by indexed journals in 2020.
The simplest method of locating most Journal Impact Factors is to Google your complete journal name, and add IF and most current year to your search:
Alternatively, Google your journal title and go to its website. Locate the “About the Journal” link; this will likely lead you to the Journal’s Impact Factor.
Journal Citation Reports provides IF ranking for journals but is limited to the citation data for journals indexed in Web of Science. SCImago Journal Rank includes 15,000+ journals but uses the quartile system of journal ranking.