Impact Factor, Metrics, Journal Rankings, Research Guide

What is Impact Factor & How is it Calculated? Guide 2026

What is Impact Factor and How is it Calculated?

The Complete Beginner’s Guide for Researchers (2026)

Last Updated: March 2026  |  By ResearchJournalRank Team

Introduction

If you are a researcher, PhD student, or academic, you have almost certainly heard the term “Impact Factor” – but do you actually know what it means, how it is calculated, and why it matters for your career? The Impact Factor (IF) is the single most widely used metric for evaluating the prestige and influence of academic journals worldwide, and understanding it is essential for making smart publishing decisions.

Despite its widespread use, the Impact Factor is frequently misunderstood, misapplied, and even criticized. Many researchers confuse it with CiteScore, SJR, or the H-Index. Others use it to evaluate individual papers or researchers, which is not its intended purpose.

This comprehensive guide explains everything you need to know about Impact Factor in 2026: what it is, who calculates it, the exact formula with worked examples, how to check any journal’s IF, its limitations, and how it compares to alternative metrics like CiteScore and SJR. Whether you are a first-year PhD student or a seasoned professor, this guide will give you complete clarity on the most important number in academic publishing.

What is Impact Factor?

The Impact Factor (IF), also called Journal Impact Factor (JIF), is a metric that measures how frequently the average article published in a specific journal has been cited in a particular year. It is calculated and published annually by Clarivate Analytics through the Journal Citation Reports (JCR).

In simple terms: A journal’s Impact Factor tells you how many times, on average, its recently published articles were cited by other researchers. A higher IF means the journal’s articles are cited more frequently, which generally indicates greater influence and prestige in the field.

Key Facts About Impact Factor:

• Created by: Eugene Garfield, founder of the Institute for Scientific Information (ISI), in 1955. First calculated in 1975.

• Current owner: Clarivate Analytics (acquired ISI/Thomson Reuters)

• Published in: Journal Citation Reports (JCR), released annually in June

• Latest release: JCR 2025 (released June 2025, covering 2024 citation data)

• Coverage: Only journals indexed in the Web of Science Core Collection receive an Impact Factor

• Scope: Approximately 22,000+ journals across SCIE, SSCI, AHCI, and ESCI

How is Impact Factor Calculated? The Formula Explained

The Impact Factor formula is straightforward, but the details matter. Here is the exact calculation:

The Impact Factor Formula:

IF (Year N) = Citations received in Year N to articles published in Years N-1 and N-2 ÷ Number of citable articles published in Years N-1 and N-2

Step-by-Step Worked Example:

Let’s calculate a hypothetical Impact Factor for “Journal X” for the year 2024:

Step 1 – Count articles published: Journal X published 200 citable articles in 2022 and 250 citable articles in 2023. Total citable articles = 200 + 250 = 450.

Step 2 – Count citations received: In 2024, articles from all journals in Web of Science cited Journal X’s 2022 and 2023 articles a total of 1,350 times.

Step 3 – Apply the formula: IF (2024) = 1,350 ÷ 450 = 3.0

Result: Journal X has a 2024 Impact Factor of 3.0, meaning its articles published in the previous two years were cited an average of 3 times each.

What Counts as a “Citable Article”?

Included (denominator): Research articles, reviews, and proceedings papers. These are considered “citable items.”

Excluded (denominator): Editorials, letters, news items, corrections, meeting abstracts. These are NOT counted as citable items.

However (numerator): ALL citations to the journal count in the numerator, regardless of the document type being cited. This asymmetry is one of the most criticized aspects of the IF calculation.

What is the 5-Year Impact Factor?

The 5-Year Impact Factor works the same way but uses a 5-year citation window instead of 2 years. This is particularly useful for fields where research takes longer to be cited, such as humanities, social sciences, and mathematics. The formula is: IF-5 (Year N) = Citations in Year N to articles published in Years N-1 through N-5 ÷ Citable articles published in Years N-1 through N-5.

Impact Factor Examples: Highest IF Journals in 2026

Journal Name	IF (JCR 2025)	Field	Publisher
CA: A Cancer Journal for Clinicians	503.1	Oncology	Wiley / ACS
The Lancet	98.4	General Medicine	Elsevier
New England Journal of Medicine	96.2	General Medicine	NEJM Group
Nature	50.5	Multidisciplinary	Springer Nature
Science	44.7	Multidisciplinary	AAAS
IEEE Trans. Pattern Analysis & MI	18.6	Computer Science / AI	IEEE
PLOS Medicine	9.9	General Medicine (OA)	PLOS
BMJ Open	2.3	General Medicine (OA)	BMJ
Cureus	1.2	General Medicine (OA)	Springer Nature

Source: JCR 2025 (Clarivate, released June 2025). Explore all journals on Research Journal Rank.

Notice the enormous range: from 503.1 (CA Cancer Journal) to 1.2 (Cureus). Impact Factor varies dramatically across fields – medical journals typically have much higher IFs than computer science or mathematics journals because of different citation patterns.

What is a “Good” Impact Factor?

There is no universal answer to this question because citation patterns vary enormously between fields. What is considered a good IF depends entirely on the discipline:

Medicine / Biomedical Sciences: IF > 5 is considered good. IF > 10 is excellent. IF > 30 is elite.

Engineering / Technology: IF > 3 is considered good. IF > 5 is excellent. IF > 10 is elite.

Computer Science: IF > 3 is considered good. IF > 5 is excellent. IF > 10 is elite. (CS also values conference publications heavily.)

Social Sciences: IF > 2 is considered good. IF > 4 is excellent. IF > 8 is elite.

Mathematics: IF > 1 is considered good. IF > 2 is excellent. IF > 3 is elite. (Math has inherently lower citation rates.)

Arts & Humanities: Many humanities journals do not have an IF at all. When they do, IF > 1 is considered very good.

The key principle: always compare Impact Factors within the same field. An IF of 3.0 in mathematics is outstanding, while the same IF in medicine would be considered average.

How to Check a Journal’s Impact Factor

Method 1 – Journal Citation Reports (JCR): The official source. Visit jcr.clarivate.com (requires institutional subscription). Search by journal title or ISSN. The latest JCR was released in June 2025.

Method 2 – Web of Science Master Journal List: Visit mjl.clarivate.com to check if a journal is indexed in WoS. Journals in the Core Collection are eligible for IF.

Method 3 – Journal Websites: Most journals display their IF on their homepage or “About” page. However, always verify with official JCR data as some journals display inflated or outdated figures.

Method 4 – Research Journal Rank: While we display SJR, CiteScore, and H-Index (Scopus-based metrics), you can use our database to identify high-ranking journals and then cross-check their IF on JCR.

Method 5 – SCImago (scimagojr.com): SCImago does not show Impact Factor (it shows SJR), but you can use it to identify Scopus-indexed journals and their quartile rankings as a free alternative.

Warning: NEVER trust a journal that claims a high Impact Factor without verification on JCR. Predatory journals frequently display fake or self-invented “impact factors” to attract submissions.

Limitations and Criticisms of Impact Factor

Despite its widespread use, the Impact Factor has significant limitations that every researcher should understand:

1. Field Bias: Citation patterns differ dramatically across disciplines. Medical journals have much higher IFs than mathematics or humanities journals. Comparing IF across fields is meaningless.

2. Skewed Distribution: A small number of highly cited articles can inflate a journal’s IF. Most articles in a journal are cited less than the IF suggests. The IF is a mean, not a median.

3. Denominator Manipulation: The asymmetry between what counts in the numerator (all citations) and denominator (only “citable” items) can be exploited. Publishing more editorials/letters increases citations without adding to the denominator.

4. Review Journal Bias: Review articles are cited more than original research. Journals that publish many reviews tend to have higher IFs, which does not necessarily reflect research quality.

5. Self-Citation: Some journals encourage self-citation to boost their IF. Clarivate monitors this and has suppressed journals for excessive self-citation.

6. Not for Individual Evaluation: The IF measures journal-level performance, NOT individual article quality. A paper in a high-IF journal may be poorly cited, and a paper in a low-IF journal may be groundbreaking. DORA (Declaration on Research Assessment) explicitly recommends against using IF for individual evaluation.

7. Gaming and Negotiation: Publishers have been known to negotiate with Clarivate about which items count as “citable,” leading to sudden IF changes that have nothing to do with research quality.

8. Two-Year Window: The 2-year citation window may not capture the full impact of research in slow-citing fields. The 5-Year IF partially addresses this.

Impact Factor vs Other Journal Metrics: Complete Comparison

Metric	Provided By	Window	Free?	Best Use Case
Impact Factor (JIF)	Clarivate (Web of Science)	2 years	No (paid JCR)	Prestige, tenure decisions, hiring
5-Year Impact Factor	Clarivate (Web of Science)	5 years	No (paid JCR)	Slower-citing fields (humanities, social sciences)
CiteScore	Elsevier (Scopus)	4 years	Yes	Free alternative to IF, broader view
SJR	SCImago (Scopus data)	3 years	Yes (scimagojr.com)	Prestige-weighted ranking, quartile classification
SNIP	CWTS (Scopus data)	3 years	Yes	Cross-field comparisons (normalized)
Eigenfactor	Clarivate	5 years	Yes (eigenfactor.org)	Total journal influence (size-independent)
H-Index	Multiple databases	Lifetime	Yes	Author & journal lifetime impact

Recommendation: Use multiple metrics together. Impact Factor for prestige context, CiteScore for free Scopus comparison, SJR for quartile ranking, and H-Index for lifetime impact.

DORA: The Movement Against Impact Factor Misuse

The San Francisco Declaration on Research Assessment (DORA), launched in 2012, is an international initiative signed by thousands of institutions, funders, and researchers. It explicitly recommends against using Impact Factor to evaluate individual researchers, hiring decisions, or grant applications.

DORA’s key recommendation: Do not use journal-based metrics such as Impact Factor as a surrogate measure of the quality of individual research articles, to assess an individual scientist’s contributions, or in hiring, promotion, or funding decisions.

While DORA has gained significant traction globally, many institutions – particularly in Asia, Europe, and developing countries – continue to rely heavily on IF for research evaluation. As a researcher, you should be aware of DORA’s principles and advocate for more holistic research assessment at your institution.

Frequently Asked Questions (FAQs)

Q1: What is a journal’s Impact Factor?

Impact Factor is a metric calculated by Clarivate Analytics that measures how frequently the average article in a journal was cited in the previous two years. It is published annually in the Journal Citation Reports (JCR). Only journals indexed in the Web of Science Core Collection receive an official Impact Factor.

Q2: How is Impact Factor calculated?

IF = Citations received in the current year to articles published in the previous two years, divided by the number of citable articles published in those two years. For example, if 1,000 citations were received in 2024 to articles published in 2022–2023, and 400 citable articles were published, the IF = 1,000/400 = 2.5.

Q3: Who publishes the Impact Factor?

Clarivate Analytics publishes the Impact Factor through the Journal Citation Reports (JCR), released annually in June. The latest release (June 2025) covers 2024 citation data.

Q4: Is Impact Factor the same as CiteScore?

No. Impact Factor (Clarivate/WoS) uses a 2-year citation window and counts only citable items in the denominator. CiteScore (Elsevier/Scopus) uses a 4-year window and includes all document types. CiteScore values are typically higher and are freely available, while IF requires a paid JCR subscription.

Q5: Do all journals have an Impact Factor?

No. Only journals indexed in the Web of Science Core Collection (SCIE, SSCI, AHCI, ESCI) receive an Impact Factor. Many legitimate journals indexed in Scopus or other databases do not have an IF. Not having an IF does not mean a journal is low quality.

Q6: What is a good Impact Factor?

It depends entirely on the field. In medicine, IF > 5 is good; in mathematics, IF > 1 is good. Always compare IF within the same subject category, never across disciplines.

Q7: Can I use Impact Factor to evaluate my own research quality?

No. The IF is a journal-level metric, not an article-level or author-level metric. A highly cited paper can appear in a low-IF journal, and a poorly cited paper can appear in a high-IF journal. DORA (Declaration on Research Assessment) explicitly advises against using IF for individual evaluation.

Q8: How often is Impact Factor updated?

Once per year. Clarivate releases the new JCR (including updated Impact Factors) every June. The JCR 2025 release (June 2025) contains Impact Factors calculated from 2024 citation data.

Q9: Can a journal lose its Impact Factor?

Yes. Clarivate can suppress a journal’s IF for excessive self-citation, citation manipulation, or other editorial integrity concerns. Journals removed from the Web of Science Core Collection also lose their IF.

Q10: Where can I check Impact Factor for free?

The official JCR requires institutional access (paid). However, many journals display their IF on their website. For free journal metrics, use Research Journal Rank (SJR, CiteScore, H-Index, quartile) and SCImago (scimagojr.com). These Scopus-based metrics are excellent free alternatives to Impact Factor.

Conclusion

Impact Factor remains the most widely recognized and influential metric in academic publishing in 2026, despite its well-documented limitations. Understanding how it is calculated, what it means, and – critically – what it does not mean is essential for every researcher navigating the publishing landscape.

The key takeaways: IF measures journal-level citation performance over two years. It is calculated by Clarivate and published in JCR. It varies enormously by field and should never be compared across disciplines. It should not be used to evaluate individual researchers or articles. And it is just one of several useful metrics – CiteScore, SJR, SNIP, and H-Index all provide complementary perspectives.

For comprehensive journal comparison using freely available metrics, explore Research Journal Rank – your free database of 31,000+ journals with SJR scores, CiteScore, H-Index values, quartile rankings, and open access data. Compare journals and make informed publishing decisions today.