- Impact factors are calculated by Thomson Reuters, the producer of Web of Science.
- The impact factor of Journal A = number of citations to articles in Journal A in Web of Science in previous two years, divided by number of original research articles and reviews published by Journal A in the previous two years.
Where To Find Impact Factors and Journal Rankings
- Journal Citation Reports (JCR)
- Not all journals are assigned impact factors.
- No humanities journals are listed in the Journal Citation Report
Further Information on Impact Factors
- The Agony and the Ecstasy: the History and the Meaning of the Journal Impact Factor (2005 paper by the former chairman of the company that issues impact factors)