Examples
Worked examples
- Is an instance
A hematology researcher checking Blood's current JCR entry against Leukemia's or the American Journal of Hematology's separately computed JIF before deciding where a manuscript on a specific blood disorder is likely to reach the widest specialist readership, while treating the comparison as journal-level only, not a measure of any individual paper's quality.
- Is an instance
A grants or promotion office noting in an internal metrics reference that Blood is Science Citation Index Expanded-indexed and therefore receives an annual Clarivate JIF, distinct from Scopus's CiteScore for the same journal, which uses a different citation window and denominator.
Counter-examples
Looks similar, but isn't
- Not an instance
Citing a single Blood impact-factor figure pulled from an aggregator site as the current, authoritative number without noting which JCR release year it reflects -- reported figures for Blood diverge from one another and change with each annual JCR update.
- Not an instance
Using Blood's high JIF to argue that a specific paper published in Blood is more rigorous than a comparable paper published in a lower-JIF hematology journal -- the JIF is a journal-level average across two years of citations, not an article-level or author-level quality measure, per DORA.
Editorial commentary
The Journal Impact Factor (JIF) for Blood is a specific, illustrative instance of the general Journal Impact Factor metric published annually by Clarivate in the Journal Citation Reports (JCR). Blood is the flagship, weekly peer-reviewed journal of the American Society of Hematology (ASH), published continuously since 1946. This page is specifically about the hematology journal — not about the common English word ‘blood,’ which is not a journal and has no impact factor.
What the number actually measures
The JIF is a ratio: citations received in a given JCR data year to a journal’s citable items (original research articles and reviews) published in the two preceding years, divided by the number of those citable items. Blood (ISSN 0006-4971 print, 1528-0020 online) is indexed in Clarivate’s Science Citation Index Expanded and receives its own JIF computed the same mechanical way as every other JCR-indexed title — the formula does not vary by field, journal age, or publisher.
A note on the current figure
Reported figures for Blood’s JIF vary depending on the source and the JCR release being cited. ASH’s own hematology.org materials have referenced a figure near 23.9 for a recent release, describing Blood as the most-cited journal in hematology by total citation volume. Third-party JCR-tracking aggregators (BioxBio, JournalsInsights, journalmetrics.org) report figures generally in the low-to-mid 20s for recent years, and one ASH-affiliated results page has referenced 21.0 tied specifically to the 2023 JCR release. These figures do not fully agree with one another, which is typical when different JCR release years or aggregator caching lags are being compared rather than a genuine discrepancy in the underlying citation data. Treat any single number you see cited as time-stamped to a specific JCR release — Clarivate updates JCR every June — and check ashpublications.org/blood or jcr.clarivate.com directly for the current, release-dated figure before citing it in a formal context such as a CV, grant application, or tenure file.
Worked example
If Blood published 900 citable items across two preceding years, and those items collectively received about 20,000 citations in the JCR data year, the resulting JIF would be 20,000 / 900 ≈ 22.2 — the same arithmetic Clarivate applies to every JCR-indexed journal, from a small society title to a high-volume subspecialty flagship like Blood. Blood’s combination of high weekly publication volume (52 issues a year) and consistently strong citation counts is part of why it ranks as the most-cited hematology journal even while its per-item JIF sits below some lower-volume specialty titles.
Why the figure matters in hematology specifically, and what it doesn’t tell you
Within hematology, Blood’s JIF is often used informally as a benchmark against comparable subspecialty journals such as Leukemia or the American Journal of Hematology, and against Blood’s own sister publication, Blood Advances. A high JIF reflects that Blood’s published articles are, on average, cited frequently within the two-year citation window — it does not mean every individual article is highly cited, nor that a specific paper published in Blood is inherently more rigorous than a comparable paper published elsewhere. Per DORA (San Francisco Declaration on Research Assessment) and CoARA’s responsible-assessment guidance, journal-level metrics like the JIF should not substitute for evaluating the actual content of a specific paper, or the contributions of a specific researcher, in hiring, promotion, or funding decisions.
Related terms
- Journal Impact Factor (JIF) — the general metric this page illustrates with one journal’s current figure.
- Journal Citation Reports (JCR) — the Clarivate product that publishes the JIF annually.
- New England Journal of Medicine’s Journal Impact Factor (JIF) — another single-journal illustrative instance, for cross-field comparison.
- Cell’s Journal Impact Factor (JIF) — another single-journal illustrative instance.
- CiteScore — Elsevier/Scopus’s competing journal-level metric for the same journal, with a different window and denominator.
- DORA (San Francisco Declaration on Research Assessment) — the reform commitment behind the over-reliance caveat above.
Machine-readable encodings
Use in your systems
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