The impact factor is just one quantitative factor to use in evaluating or comparing a journal's relative importance to others in the same field. It identifies the frequency with which an average article from a journal is cited in a particular year.
The 2010 impact factor for Journal X would be calculated by dividing the number of 2010 citations to articles appearing in Journal X during 2008-2009 by the number of articles published in Journal X in 2008-2009.
See the Thomson Reuters website for more information.
Journals included in Web of Science
Overview of Journal Citation Reports (JCR)
The established source for journal rankings (including impact factors) is the Journal Citation Reports (JCR) database.
In addition to Impact Factors, you can also find the following metrics in JCR: Total number of cites to a journal in a given year, 5-year Impact Factor, Immediacy Index, the total number of articles in the journal published in a given year, Cited Half-Life, Eigenfactor Score, and Article Influence Score.
Please refer to the Definitions/Terminology tab above to learn more about these metrics.
Accessing the JCR Database
1. Open the JCR database
NOTE: JCR is also available within Web of Knowledge, by clicking on the Additional Resources tab at the top
2. Select a JCR Edition (Science or Social Sciences) and year
3. Select a Search Option:
- View a group of journals by subject category, publisher, or country/territory
- Search for a specific journal (by full or abbreviated journal title, title word or ISSN)
- View all journals