Impact Factor Calculator
Enter the total citations a journal received in the target year along with the number of citable articles it published in each of the two preceding years to get the standard 2-year Impact Factor. Switch to the 5-year tab to include a broader citation window, or use the immediacy index mode to measure how quickly a journal's articles attracted citations in the same year they were published. Results update instantly as you type, with a worked breakdown and a reference table comparing your result against typical quartile thresholds in the discipline you select.
Formula
Worked example
A journal received 1,370 citations in 2024 to articles it published in 2022 (120 articles) and 2023 (115 articles). Impact Factor = 1,370 / (120 + 115) = 1,370 / 235 = 5.830. This score would place the journal in Q1 for mathematics or Q2 for environmental sciences, but only Q3 for clinical medicine.
What is the Journal Impact Factor?
The Journal Impact Factor (JIF) is the most widely used metric for comparing the relative influence of academic journals within the same field. It was created by Eugene Garfield in the 1960s and has been published annually by Clarivate Analytics through the Journal Citation Reports (JCR) since 1975. The 2-year JIF is calculated by dividing the number of citations a journal receives in a given year to content it published in the two preceding years by the total count of citable items (original research articles and reviews) published in those two years. The result estimates the average number of citations each article attracted during the measurement window. A journal with an IF of 5 is, on average, cited five times per article per year over that window. The metric is intentionally simple so it can be compared across journals in the same subject category, though it is easily misinterpreted across disciplines where citation cultures differ.
How to use this calculator
Choose the metric you want in the "Metric to calculate" dropdown. For the standard 2-year Impact Factor, enter the total citations the journal received in the target year (citations to content published only in the two preceding years, as counted in Web of Science) and the count of citable articles it published in each of those two years. For the 5-year Impact Factor, enter five years of article counts plus the corresponding citation total. For the Immediacy Index, enter citations received in a single year to articles published in that same year, along with the article count for that year. Select the closest discipline to see your result placed against typical Q1 and Q2 benchmarks for that field. The "citable items" count should include only original research articles and reviews; editorials, letters, and corrections are excluded from the denominator even though citations to them appear in the numerator.
2-year vs. 5-year Impact Factor: which to use?
The 2-year window suits fast-citation fields like molecular biology, clinical medicine, and chemistry, where most citations arrive within two years of publication. For disciplines with slower citation cycles - mathematics, social sciences, humanities, and some engineering subfields - the 5-year Impact Factor is a more representative measure because significant citations may arrive three to five years after publication. Clarivate publishes both the 2-year and 5-year IFs in the Journal Citation Reports. A journal whose 5-year IF is substantially higher than its 2-year IF is likely publishing foundational work with a long citation tail; the opposite pattern may indicate a journal whose influence is fading.
Limitations and common misuses
Impact factors are valid only for comparing journals in the same subject category in the same year. Using them to compare a mathematics journal against a biomedical journal, or to evaluate individual researchers (rather than journals), is methodologically unsound and has been explicitly criticised by the San Francisco Declaration on Research Assessment (DORA) and the Leiden Manifesto. The metric can be artificially inflated by publishing large numbers of highly-cited review articles (which count in the numerator but can be excluded from the denominator), by self-citation practices, and by the asymmetric rule that counts all incoming citations in the numerator but restricts the denominator to only research articles and reviews. For a more complete picture of a journal's reach, combine the IF with the CiteScore (Scopus), the SCImago Journal Rank (SJR), and the Source-Normalised Impact per Paper (SNIP), which each correct for different biases.
Typical Impact Factor thresholds by discipline (2023 JCR)
| Discipline | Q1 threshold (top 25%) | Q2 threshold (top 50%) | Notes |
|---|---|---|---|
| Molecular Biology / Biochemistry | >10 | >5 | Fastest-citation field; highest raw IFs |
| Clinical Medicine | >8 | >4 | Large citation volumes from broad readership |
| Chemistry | >6 | >3 | Varies by subfield (organic vs. analytical) |
| Environmental Sciences | >5 | >2.5 | Growing rapidly with sustainability research |
| Engineering | >4 | >2 | Lower than life sciences; applied focus |
| Social Sciences | >3 | >1.5 | Slower citation cycles; books matter more |
| Mathematics | >2 | >1 | Slowest-citation discipline; 5-year IF preferred |
| Humanities | >1 | >0.5 | Very slow cycles; IF is rarely meaningful |
Approximate Q1 and Q2 thresholds differ widely by field. Always compare within the same subject category.
Frequently asked questions
What is a good Impact Factor?
There is no single threshold that defines a "good" impact factor because the metric is discipline-specific. In molecular biology and clinical medicine, top-tier journals typically exceed an IF of 10. In mathematics or humanities, a journal with an IF of 2 may rank in the top 25% of its category. Always compare journals within the same Clarivate subject category and the same year. Use the discipline selector in this calculator to see approximate Q1 and Q2 thresholds for your field.
What counts as a citable item in the denominator?
Clarivate counts only original research articles and review articles as citable items in the denominator of the JIF calculation. Editorials, letters to the editor, corrections, retractions, news items, and meeting abstracts are excluded, even though citations to those items do count in the numerator. This asymmetry can inflate the impact factor if a journal publishes highly-cited editorials or commentary pieces. When you enter article counts in this calculator, include only research articles and reviews.
Why do I get a different result from the official JIF?
The official Clarivate Impact Factor is calculated from the full Web of Science citation database, which includes journal-level deduplication, document-type classification by Clarivate's editorial team, and the specific citation window tracked by JCR. If you calculate using raw citation counts from a different source (Scopus, Google Scholar, or PubMed), the numerator will differ because those databases use different indexing rules. This calculator computes the ratio from the numbers you enter; it will match the official JIF only if your inputs come from Clarivate's JCR data.
What is the Immediacy Index?
The Immediacy Index measures how quickly a journal's articles attract citations within the same calendar year they are published. It equals the number of citations in year X to articles published in year X, divided by the count of citable items published in year X. A high Immediacy Index suggests the journal publishes timely, fast-disseminating research. It is particularly useful in rapidly evolving fields where the 2-year window may still lag behind the real citation curve.
Can I use the Impact Factor to evaluate a researcher or author?
No. The Impact Factor is a property of a journal, not of individual articles or authors published in it. Using a journal's IF to credit or rank a researcher is widely criticised and has been condemned by the San Francisco Declaration on Research Assessment (DORA) and the International Mathematical Union, among others. For author-level citation analysis, use metrics such as the h-index, total citation count, or the Article Influence Score, which are tied to the actual articles and their individual citation histories.
How long does it take for a new journal to receive an Impact Factor?
A new journal must be indexed in Web of Science for at least two full calendar years before it can receive an official Impact Factor from Clarivate, because the calculation requires two preceding years of citable content. The first official IF typically appears in the Journal Citation Reports three years after the journal's first indexed issue. During that waiting period, the journal may appear in JCR with citation data but without a calculated IF.
What is the difference between Impact Factor and CiteScore?
The Impact Factor (Clarivate, Web of Science) and CiteScore (Elsevier, Scopus) measure similar things but differ in scope and methodology. CiteScore uses a 4-year citation window, includes more document types in both the numerator and denominator (reducing the asymmetry that inflates the JIF), and draws from the Scopus database, which indexes more journals than Web of Science. As a result, CiteScore is generally more stable year-to-year and harder to manipulate. Neither is universally superior; researchers often consult both.