What is an Impact Factor?
The Impact Factor (IF) is the average number of times the articles in a journal were cited. It is used as a rough measure of a journal's influence, and in Japanese academic medicine it is widely used in research assessment and in choosing where to submit.
The formula
A journal's Impact Factor for a given year is the average number of citations received that year by the articles it published in the previous two years.
JIF (2025) = citations in 2025 to articles published in 2023–2024 ÷ number of original articles and reviews published in 2023–2024
Only original articles and reviews (citable items) count in the denominator, but citations to editorials and letters are counted in the numerator. This asymmetry between numerator and denominator is the oldest criticism of the Impact Factor. Journals that publish many reviews tend to score higher.
The actual distribution — 898 medical journals
Measured values for the 898 medical journals on this site, as a reference for the question “how high is high?”.
| Percentile | IF |
|---|---|
| Minimum | 0.5 |
| 25th percentile (Q4 boundary) | 2.6 |
| Median | 3.8 |
| 75th percentile (Q1 boundary) | 6.5 |
| 90th percentile | 11.8 |
| 95th percentile | 22.6 |
| Maximum | 685.2 |
Half of all journals have an IF below 3.8. Only 13% have an IF above 10.
| Threshold | Journals | Share |
|---|---|---|
| IF 2 or higher | 810 | 90.2% |
| IF 3 or higher | 605 | 67.4% |
| IF 5 or higher | 318 | 35.4% |
| IF 10 or higher | 115 | 12.8% |
| IF 20 or higher | 58 | 6.5% |
| IF 50 or higher | 14 | 1.6% |
“High” depends on the field
Impact Factors must not be compared across fields, because citation habits differ. Fields closer to basic science and fields with more researchers have higher numbers.
| Specialty | Journals | Median | Maximum |
|---|---|---|---|
| Oncology | 42 | 6.8 | 685.2 |
| Medicine, General & Internal | 40 | 6.2 | 109.0 |
| Cardiac & Cardiovascular Systems | 41 | 6.0 | 50.2 |
| Endocrinology & Metabolism | 33 | 5.7 | 39.1 |
| Psychiatry | 38 | 5.5 | 79.5 |
| Hematology | 38 | 4.8 | 47.8 |
| Geriatrics & Gerontology | 32 | 4.3 | 25.0 |
| Clinical Neurology | 43 | 4.3 | 54.6 |
| Ophthalmology | 29 | 4.2 | 16.2 |
| Infectious Diseases | 42 | 4.1 | 29.4 |
| Respiratory System | 36 | 4.0 | 34.7 |
| Gastroenterology & Hepatology | 39 | 3.9 | 57.5 |
| Radiology, Nuclear Medicine & Medical Imaging | 40 | 3.8 | 20.1 |
| Urology & Nephrology | 41 | 3.7 | 46.7 |
| Rheumatology | 33 | 3.5 | 33.7 |
| Nursing | 42 | 3.4 | 8.7 |
| Orthopedics | 40 | 3.4 | 20.1 |
| Obstetrics & Gynecology | 45 | 3.4 | 20.1 |
| Dermatology | 32 | 3.2 | 12.3 |
| Critical Care Medicine | 39 | 3.2 | 22.0 |
| Anesthesiology | 27 | 3.2 | 10.3 |
| Surgery | 36 | 3.0 | 15.6 |
| Pediatrics | 40 | 2.9 | 17.1 |
| Neurosurgery | 31 | 2.5 | 13.1 |
| Emergency Medicine | 35 | 2.3 | 11.0 |
| Otorhinolaryngology | 31 | 2.0 | 5.7 |
By median, the highest field is more than three times the lowest. A journal with an IF of 5 is only slightly above the median in oncology but in the top 10% in emergency medicine or otorhinolaryngology. Check the typical range for your own field in the specialty lists.
How to check an IF for free
Journal Citation Reports (JCR) itself requires an institutional subscription. Without one, you can use:
- The journal's official site — almost every journal posts its own Impact Factor. This is the most reliable source
- The specialty lists on this site — those published values collected by specialty (898 journals)
- Scopus CiteScore — free at scopus.com/sources, but it is a different metric and its values cannot be compared directly with the IF
Mind the year label
JCR releases the previous year's figures every June: the edition released in June 2026 is “JCR 2025”. Some aggregator sites label by release year instead, so a value labelled “2025 Impact Factor” may actually be JCR 2024. This site standardises on JCR 2025 and marks the year explicitly where it could not be confirmed.
Caveats
- It measures the journal, not the paper. Citation counts vary widely between articles in the same journal
- It cannot be compared across fields, as the table above shows
- The two-year window is short. Clinical research often has not accumulated its citations two years after publication
- When choosing where to submit, readership, whether the journal accepts your article type, the author guidelines, review time and fees matter more in practice
Frequently asked questions
Where can I look up an Impact Factor for free?
JCR itself requires an institutional subscription, but publishers post the Impact Factor of their own journals. This site collects those values by specialty. Scopus CiteScore is also freely available at scopus.com/sources.
How high does an Impact Factor need to be to count as high?
It depends on the field. The median of the 898 journals on this site is 3.8, but the median in oncology is 6.8 while in otorhinolaryngology it is 2.0. The same IF of 5 sits in opposite positions depending on the field.
When is the Impact Factor updated?
Every June, for the previous year. The edition released in June 2026 is “JCR 2025”. Some aggregator sites label by release year, so the same “2025” can refer to a different edition.
What do Q1 and Q2 mean?
Quartiles of the journals in a field ranked by Impact Factor. Q1 is the top 25%, Q4 the bottom 25%. The same journal can fall in a different quartile depending on how the field is defined.
Should I submit to the journal with the highest Impact Factor?
The Impact Factor is a journal's average citation count; it says nothing about the quality of an individual paper. Whether the readership fits, whether the journal accepts your article type, and whether the review time and fees are acceptable matter more in practice.
This site lists the Impact Factors of 898 journals by specialty. See also the author guidelines comparison and the journals that accept case reports. Last updated September 2026.