Impact Factor Calculator

A journal's impact factor is a measure of how frequently its articles are cited on average, calculated as the number of citations in a given year to articles published in the two prior years, divided by the number of citable items published in those same two years.

IF = Citations / Citable Items, where Citations is the count of citations received in the target year to articles published in the two prior years, and Citable Items is the number of research articles and reviews published in those two prior years.

Citable items are typically original research articles and review articles, the content types indexing databases count toward the denominator. Editorials, letters to the editor, news pieces, and corrections are usually excluded from the citable-item count, even though citations to them (if any) may still count in the numerator in some counting methodologies.

This depends entirely on the academic field, fast-moving, highly-cited fields like cell biology or medicine often have top journals with impact factors above 30-40, while many mathematics or humanities journals have respectable impact factors below 3. Always compare journals within the same discipline, never across fields.

The standard two-year window balances timeliness (recent enough to reflect current relevance) against giving papers enough time to accumulate citations (since citation counts build up gradually after publication). Some indexes also publish a five-year impact factor for fields where citations accumulate more slowly.

No, impact factor is a journal-level average, not a per-article measure. Citation counts within a journal are typically highly skewed, a small number of very highly-cited papers can substantially raise the average impact factor even if most articles in that same journal receive relatively few citations.

The most widely cited official impact factor comes from Clarivate's Journal Citation Reports (JCR), calculated from the Web of Science citation database. This calculator computes the same ratio from whatever citation and citable-item counts you provide, which is useful for understanding or verifying the calculation, but official published values come from JCR's own indexed data.

Yes, this is a well-documented concern in academic publishing. Practices like excessive self-citation, coercive citation (pressuring authors to cite the journal), and strategically publishing highly-citable review articles can inflate a journal's impact factor without reflecting genuine average research quality, which is part of why many researchers advocate for citation metrics to be used alongside, not instead of, other quality indicators.

No, impact factor is one of several metrics, others include the h-index, CiteScore, SCImago Journal Rank (SJR), and Eigenfactor, each weighting citations, prestige, or field normalization differently. Relying on impact factor alone is widely criticized in the research community (see the DORA declaration on research assessment) as an incomplete way to judge research quality.

Official impact factors are typically recalculated and published annually, once citation data for the relevant prior years has been fully collected and indexed, usually released in the summer following the target year.