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Understanding the Journal Impact Factor

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Within the field of journal-level bibliometrics, the most well-known measurement is the Journal Impact factor (JIF). The brainchild of Eugene Garfield, the JIF dates back nearly 70 years. (Garfield, 2006) The JIF calculation is fairly straightforward. A journal’s JIF is determined by adding the total number of citations accrued during the current JCR year by articles published in the prior two years and dividing that by the number of articles published in the prior two years.

Impact Factor Example image

(Journal Impact Factor, 2021)  This calculation approximates the average number of citations achieved by articles in that journal.  With the number of citations being a measure of impact, a higher JIF indicates that a journal is more influential within its field.

JIFs can be found by searching the database Journal Citation Reports (JCR).  JCR is available by selecting the letter J or by selecting Research Tools, after you click on the ‘All Databases’ link from the Himmelfarb Library homepage (himmelfarb.gwu.edu).


Impact Factor Article Image 1 Impact Factor Article Image 2

After you open JCR, just type in the name of your journal of interest to retrieve the most recent JIF value.  Please note that because of the way JIFs are calculated, the most recent JIFs, as of the writing of this article (September 2024), are the 2023 values. 

One of the most common questions we receive in regards to JIFs is what is a good value.  This is a difficult question to answer as citation patterns differ from one discipline to another, so a JIF that is good in one discipline may not be as well-regarded in another discipline.  However, there are some ways to determine how the JIF of a particular journal compares to other journals within that field.  One way is to look up the JIF for a particular journal and scroll down to the bottom of the page and look for the section called ‘Rank by Journal Impact Factor’.  Here you will see how that journal’s impact factor ranks compared to other journals within a particular category.  For instance, at the bottom of the page for the journal Lancet, it indicates that it’s JIF is the highest among all 325 journals that JCR has characterized as ‘Medicine, General & Internal’.

For more help with using JIFs, please contact the Himmelfarb Library to set up an appointment (himmelfarb@gwu.edu / 202-994-2962).

  1. Garfield, E. (2006). The History and Meaning of the Journal Impact Factor. JAMA 295(1), 90-93. doi: 10.1001/jama.295.1.90.
  2. Journal Impact Factor (2021). Clarivate Glossary. Retrieved September 24, 2024 from https://jcr.help.clarivate.com/Content/jcr3-glossary.htm