Journal Impact Factor

The journal impact factor (JIF) is a metric calculated annually by Clarivate (called Clarivate Analytics until 2020) that measures the average number of citations received per article published in a specific journal during the two preceding years. It serves as a proxy for the relative importance of a journal within its field, helping researchers decide where to submit manuscripts and helping evaluators gauge the visibility of published work.

The impact factor remains one of the most widely referenced indicators in scholarly communication. Tenure and promotion committees, funding bodies, and institutional rankings frequently use it as a shorthand for research quality, even though it measures journal level citation averages rather than the merit of individual articles. Understanding the impact factor is essential for early career researchers choosing target journals, for librarians making subscription decisions, and for bibliometricians studying the structure of scientific publishing. Critics argue that over reliance on the metric can distort research incentives, favoring fields with high citation density and discouraging publication in specialized or emerging journals.

Clarivate calculates the impact factor by dividing the number of citations received in a given year by the number of citable items (original research articles and reviews) published in the journal during the two previous years. For example, if a journal published 200 citable items in 2023 and 2024, and those items received 600 citations in 2025, the 2025 impact factor would be 3.0.

The calculation excludes editorials, letters, and news items from the denominator but counts citations to all content types in the numerator, which can inflate the metric for journals that publish many non research items. Annual release occurs through the Journal Citation Reports (JCR) database, typically in June: the 2026 release, published on 17 June 2026, carries the 2025 impact factors. Since the 2023 release, Clarivate has given an impact factor to all journals in the Web of Science Core Collection, including those in the Arts & Humanities Citation Index and the Emerging Sources Citation Index, and has reported it to one decimal place rather than three. Since the 2025 release, citations to and from retracted items are left out of the numerator, while retracted items still count in the denominator. Researchers can also consult alternative journal level metrics such as CiteScore, SJR, and SNIP to obtain complementary perspectives on journal influence.

Use the impact factor as one input when selecting journals for manuscript submission and when comparing journals within the same discipline. Do not use it to judge an individual article or researcher: in a systematic review, study quality is appraised with risk of bias tools, and in hiring, promotion and funding decisions the San Francisco Declaration on Research Assessment (DORA) advises against journal based metrics. Avoid using the impact factor to compare journals across different fields, as citation practices vary substantially between disciplines.

Comparing impact factors across unrelated fields is misleading because citation norms differ dramatically; a factor of 2.0 may be excellent in mathematics but below average in biomedical sciences. Treating a high impact factor as proof that every article in the journal is high quality ignores the skewed distribution of citations within any journal. Using the impact factor as the sole criterion for journal selection can lead researchers to overlook well regarded specialist journals that serve their target audience more effectively.

A researcher studying health economics is deciding between two journals. Journal A has an impact factor of 4.2 and publishes broadly across public health, while Journal B has an impact factor of 2.8 but is the leading outlet in pharmacoeconomics. Although Journal A has the higher metric, Journal B reaches the specialized audience most likely to cite and apply the work. The researcher chooses Journal B after confirming its standing through CiteScore, editorial board composition, and recent publication topics.