Define Journal Impact Factor
The full definition of journal impact factor (JIF) — the formula, how Clarivate computes it, the highest-IF journals in 2026, and how it compares to CiteScore and SJR.
The Journal Impact Factor (JIF) is a proprietary metric used to rank the relative importance of a journal within its scientific field. Calculated annually by Clarivate, it represents the average number of citations received by articles published in that journal during the preceding two years.
A high Impact Factor is often seen as a sign of high prestige and rigorous selection criteria. However, modern researchers are encouraged to look at 'Field-Weighted' metrics as well, as citation habits differ greatly between fields like Mathematics and Medicine. JournalsHub.online provides a 5-year historical trend for these factors to help you identify journals that are consistently growing in influence.
How is Journal Impact Factor Calculated?
Impact Factor is computed yearly by Clarivate and published in the Journal Citation Reports (JCR). The formula:
Worked example. A journal received 1,200 citations in 2025 to articles it published across 2023 and 2024. In those two years it published 300 citable articles. Its 2025 Impact Factor = 1200 / 300 = 4.0. Clarivate releases this number in the JCR each June.
Highest Impact Factor Journals 2026
Top-ranked journals by 2026 JCR Impact Factor — across medicine and the life sciences:
- CA: A Cancer Journal for Clinicians — IF > 250 (oncology review)
- The Lancet — IF ~98 (general medicine)
- New England Journal of Medicine (NEJM) — IF ~96 (general medicine)
- Nature — IF ~64 (multidisciplinary science)
- Cell — IF ~64 (cell biology)
- Nature Medicine — IF ~58 (translational medicine)
- Science — IF ~56 (multidisciplinary science)
For a live ranked list updated with each JCR release, see the Top Searched Journals hub.
Impact Factor vs CiteScore vs SJR
| Metric | Source | Window | Notes |
|---|---|---|---|
| Impact Factor | Clarivate JCR | 2 years | WoS-indexed journals only. Most-cited measure in medicine + sciences. |
| CiteScore | Elsevier Scopus | 4 years | Wider Scopus catalog. Often higher than IF for the same journal. |
| SJR | SCImago | 3 years | Weights citations by source prestige (like PageRank). |
Full comparison: Impact Factor vs CiteScore.
Searching Impact Factor by ISSN
Already have the journal's ISSN? Paste it into our ISSN Checker to get the latest JCR Impact Factor, CiteScore, quartile, and indexing badges in one panel. We track impact factor for 6,000+ journals with annual updates from the official JCR release.
Important Caveats
- Field-dependent. A 3.0 IF in pure mathematics is exceptional; the same value is below average in clinical medicine. Always benchmark within the same discipline.
- Doesn't measure individual papers. Half of a journal's citations come from ~10% of its articles. A high-IF journal does not guarantee a high-cited paper.
- Vulnerable to gaming. Some editors increase IF via excessive self-citation or review issues. JCR now publishes a Journal Self-Citation Ratio to flag this.
- "Universal Impact Factor" / "Global Impact Factor" are not real. Only Clarivate's JCR Impact Factor is the recognized metric. Predatory journals frequently quote fake variants.