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Impact Factor

The Impact Factor is a metric used to evaluate the influence and importance of academic journals within a particular field.

It is calculated and published annually by Clarivate Analytics (previously Thomson Reuters) as part of the Journal Citation Reports (JCR).

Some key points about the Impact Factor


The Impact Factor represents the average number of citations received by articles published in a specific journal within a two-year period.

It is calculated by dividing the number of citations in the current year to articles published in the previous two years by the total number of citable articles in that same period.


The formula for calculating the Impact Factor is as follows:

Impact Factor = Total citations in year X / Total citable articles published in years X-1 and X-2

Time Window:

The Impact Factor is typically calculated and reported on an annual basis, covering a specific period.

For example,

The Impact Factor for a journal in 2020 would be based on citations received in 2020 to articles published in 2018 and 2019.

Journal Ranking:

Journals are ranked based on their Impact Factor within their respective fields. Higher Impact Factors are generally associated with journals that have a higher number of citations, indicating that their articles are highly influential and frequently cited by other researchers.


Impact Factors are specific to individual journals and cannot be compared across different fields or disciplines. Each field has its own average citation rates, and therefore, comparing Impact Factors between fields is not meaningful.


While the Impact Factor is widely used, it has certain limitations. It may be biased towards journals in certain fields with higher citation rates, and it can be influenced by a small number of highly cited articles. Additionally, it does not consider the quality of individual articles or the impact of research beyond the journal level.