Impact Factor Calculator

Enter the metric year to set up the tables.

Official values come only from Clarivate's Journal Citation Reports (JIF) and Elsevier's Scopus (CiteScore), counted from their own indexes. This calculator reproduces the arithmetic on numbers you supply.

How to Use the Impact Factor Calculator

1. 1. Set the metric year. For a JIF this is the JCR year — the year whose citations are counted, published in the following June. For CiteScore it is the CiteScore year.
2. 2. Fill in the JIF table. For each of the five previous years, enter the citations that year's items received in the metric year, and the citable items published that year. The first two rows give the JIF; all five give the five-year JIF.
3. 3. Fill in the CiteScore table if you want it: for each of the four years ending with the metric year, the citations received over those four years by documents published that year, and the number of documents.
4. 4. Read the results. Each metric is shown to one decimal place, as published, with the exact value and the division written out. The example button fills in a complete illustrative set.

The Formulas

For a JCR year Y, Clarivate's Journal Impact Factor is:

The five-year JIF stretches the window to five years: citations in Y to items from Y−1 to Y−5, divided by the citable items from those five years. Citable items are articles and reviews. Editorials, letters and news items are left out of the denominator, but citations to them still count in the numerator — the asymmetry most criticised in the JIF. Since its 2023 release, JCR displays the JIF to one decimal place.

CiteScore, Elsevier's metric from Scopus, uses a four-year window that includes the metric year itself:

Both sides count the same five document types — articles, reviews, conference papers, book chapters and data papers — so CiteScore has no numerator–denominator mismatch. It is published once a year, with a monthly CiteScore Tracker showing the current year's value as it builds.

A Worked Example

The example button fills in an illustrative journal — not a real one. With 2025 as the metric year, the results are:

In the JIF the 2023 items, cited for a second year, bring in more citations than the 2024 items in their first: articles take time to be cited, which is why a two-year window favours fields where papers are cited quickly. CiteScore's newest documents, published in the metric year itself, have had the least time of all, which pulls its value down for a journal that is growing.

Limits and Misuse

• It describes a journal, not an article. Citations are highly skewed: a few papers collect most of them, and most papers in a high-JIF journal are cited less often than the average suggests.
• It does not compare across fields. Medicine, mathematics and the humanities cite at very different rates; compare journals only within a subject category, by rank or quartile.
• It can be gamed — by front matter that attracts citations without counting as citable items, by excessive journal self-citation or by pressing authors to cite the journal. Clarivate suppresses titles whose citation patterns are anomalous.
• It is not a measure of researchers. The San Francisco Declaration on Research Assessment (DORA) asks institutions not to use journal metrics such as the JIF to judge individual articles or researchers, or in hiring, promotion and funding decisions.
• Watch for fake impact factors. Predatory journals advertise invented “impact factors” from unrelated companies. A genuine JIF appears in Clarivate's Journal Citation Reports and a genuine CiteScore in Scopus — nowhere else.

Frequently Asked Questions

How is the impact factor calculated?

Take the citations a journal received in one year to everything it published in the previous two years, and divide by the number of articles and reviews it published in those two years. For 2025, that is citations in 2025 to 2023–2024 items divided by the citable items from 2023 and 2024.

What is the difference between the impact factor and CiteScore?

The JIF comes from Clarivate's Web of Science, uses a two-year window and counts only articles and reviews in the denominator. CiteScore comes from Elsevier's Scopus, uses a four-year window that includes the current year and counts the same five document types on both sides. The two databases cover different journals, so a journal's two values cannot be compared directly.

What is a five-year impact factor?

The same calculation over a five-year window: citations in the JCR year to items from the previous five years, divided by the citable items from those years. It suits fields where papers are cited slowly, and it changes less from one year to the next.

Where can I find a journal's official impact factor?

In Clarivate's Journal Citation Reports, which most university libraries subscribe to. Journals often state their JIF on their own sites, but check it against JCR. CiteScore values can be viewed free on Scopus's source pages.

Why can't I reproduce the official JIF exactly?

Because the counts come from Clarivate's own index: which citing journals it covers, how it links each citation to an item, and which items it classes as citable. Counts from Google Scholar or the journal's own site will differ. This calculator shows the method; the official figure is the one JCR publishes.

What is a good impact factor?

It depends entirely on the field. A JIF of 3 can put a journal in the top quarter of one subject category and the bottom half of another, so JCR's quartiles and category ranks are the fair comparison. And no impact factor says anything certain about a single article in the journal.