How this calculator works
The journal impact factor is a two-year citation measure. For a factor published in year Y, the numerator counts citations in year Y to items published in years Y-1 and Y-2. The denominator counts the citable items, usually research articles and reviews, published in those same two years. Dividing gives the average number of citations per citable item. Editorials, letters and news pieces are normally excluded from the denominator even though citations to them can appear in the numerator, which is one reason the number is not a pure average. The calculator also solves for the citation count needed to reach a target factor.
Formula
impact factor = citations in the measurement year / (citable items in the previous year + citable items two years before). Citations required = target impact factor x the same citable-item total.
Worked example
A journal received 500 citations in 2025 to items published in 2023 and 2024. It published 100 citable items in 2024 and 90 in 2023, a denominator of 190. The 2025 impact factor is 500 / 190 = 2.632. To reach a factor of 3.000 with the same item counts, the journal would need 3.000 x 190 = 570 citations.
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Frequently asked questions
Which citations go in the numerator?
Citations recorded in the measurement year to any content the journal published in the previous two years. The numerator is not limited to citations of citable items, so citations to editorials or letters can raise the factor while those items are excluded from the denominator.
Are self-citations included?
Yes, in the standard Journal Impact Factor, though Clarivate publishes the figure with and without self-citations. A high self-citation share can inflate the number. Compare the self-citation-free value when judging a journal.
Can I compare impact factors across fields?
Only with care. Citation rates differ widely between fields, so a 3.0 in mathematics and a 3.0 in cell biology do not mean the same thing. Clarivate publishes field-normalised metrics such as the Journal Citation Indicator for cross-field comparison.
Does a high impact factor mean high quality?
Not necessarily. The factor measures average citations to recent items, not the quality, reproducibility or societal value of the research. It is also sensitive to a few highly cited papers and to editorial policy, so it should be one signal among several.