bioRxiv does not have an impact factor, and it never will unless its governance model changes: impact factors are calculated only for peer-reviewed journals indexed in Clarivate’s Journal Citation Reports, and bioRxiv is a preprint repository, not a journal. The “biorxiv impact factor” search that ~50-70 people run every month reflects a structural misunderstanding, not a missing data point — no amount of waiting will produce one.
bioRxiv is a free preprint server for the life sciences, operated by the non-profit openRxiv and co-founded by John Inglis and Richard Sever in 2013; it distributes unpublished, non-peer-reviewed manuscripts under persistent DOIs, which is precisely the feature set that disqualifies it from journal-level citation metrics.
What bioRxiv Is, and Why It Has No Impact Factor
bioRxiv is a repository, not a periodical: it posts complete but unpublished manuscripts in the biological sciences without editorial peer review, typically within 72 hours of submission. Its own FAQ states this without qualification: “bioRxiv is not a journal so it has no Impact Factor.”
The confusion is understandable. bioRxiv issues DOIs, assigns subject categories, displays usage metrics, and looks — to a casual visitor — like a journal homepage. But the Journal Impact Factor (JIF) is a specific, licensed Clarivate product calculated from citation counts to items indexed as “articles” in the Web of Science Core Collection over a two-year window. That calculation requires a defined editorial process and a stable, recurring publication vehicle. A repository that posts author-submitted manuscripts with no acceptance/rejection decision does not meet the definition of a “source publication,” so no JIF can be computed for it, at any citation volume.
Why Preprint Servers Are Structurally Ineligible for JCR and Scimago
Both major citation-metric systems apply the same underlying logic, even though they run on different databases. Clarivate’s Journal Citation Reports draws only from titles accepted into the Web of Science Core Collection’s journal indexes, and that acceptance process screens for editorial peer review, a named editorial board, regular publication periodicity, and bibliographic standardisation — criteria a preprint repository cannot satisfy by design. Scimago Journal Rank works from Scopus’s source list, which applies an analogous journal/serial-title gate.
- No editorial acceptance decision — bioRxiv screens submissions for plagiarism, scope, and safety, but does not accept or reject manuscripts on scientific merit, so there is no equivalent of a journal’s editorial board.
- No fixed publication periodicity — preprints post continuously, not in issues or volumes, which breaks the citation-window model both JCR and Scimago use.
- Preprints remain mutable — authors can revise a preprint indefinitely until journal publication, unlike a journal’s version of record.
This is why “biorxiv scimago” searches also return nothing: bioRxiv is absent from Scimago’s journal rankings for the identical structural reason it is absent from JCR, not because of a data-processing gap. medRxiv, bioRxiv’s sister server for health sciences launched in 2019, is ineligible under the same rule set — hence “medrxiv impact factor” is equally unanswerable in the affirmative.
bioRxiv’s ISSN, DOIs, and the Preprint Citation Index — What the Identifiers Actually Mean
bioRxiv does hold an ISSN — 2692-8205 — issued because ISSNs are assigned to any continuing serial resource for cataloguing purposes, including repositories, and are unrelated to JIF eligibility. This is a distinction most explainers on this topic skip: an ISSN registers bioRxiv as a citable, ongoing publication series in library catalogues; it does not signal peer review, and it carries no weight in Clarivate’s or Scopus’s source-selection criteria.
A second, frequently overlooked identifier detail: individual bioRxiv preprints are indexed in Clarivate’s Preprint Citation Index, a distinct Web of Science product launched to track preprint citations separately from the peer-reviewed Core Collection. Being present in the Preprint Citation Index is not the same as JCR eligibility — it is a citation-tracking layer, not a metric-generating one. bioRxiv preprints are also indexed by Crossref, Google Scholar, Semantic Scholar, and Europe PMC, and PubMed indexes preprints of NIH-funded research specifically.
| Attribute | Peer-reviewed journal | bioRxiv / medRxiv |
|---|---|---|
| Peer review before posting | Yes, editorial + referee decision | No — screening only, for scope and safety |
| JCR / Journal Impact Factor eligible | Yes, if indexed in WoS Core Collection | No — structurally excluded |
| Scimago / SJR eligible | Yes, if indexed in Scopus source list | No — same structural exclusion |
| ISSN | Yes, per title | Yes — bioRxiv: 2692-8205 (cataloguing only) |
| DOI | Yes, per article | Yes, per preprint version |
| Indexed in Web of Science Preprint Citation Index | N/A | Yes |
What Metrics Actually Apply to bioRxiv and medRxiv Preprints
bioRxiv publishes per-preprint usage data on each article’s Metrics tab: abstract views and PDF downloads, updated daily, plus altmetric attention scores that aggregate mentions in news, blogs, and social platforms. These sit within the broader altmetrics framework that NISO formalised through its Alternative Assessment Metrics project (NISO RP-25-2020), which set recommended practices for defining and reporting non-citation research metrics.
There is also downstream evidence linking preprint attention to eventual journal outcomes. A 2019 analysis of all bioRxiv preprints (Abdill & Blekhman, published in eLife and indexed at PMC6510536) found a measurable correlation between a preprint’s bioRxiv download count and the Journal Impact Factor of the journal in which it was later published — useful context, but a correlation about the destination journal, not a metric of the preprint itself.
- Abstract and PDF views — updated daily on the preprint’s own page.
- Altmetric attention score — tracks news, policy, and social-media mentions.
- Citation counts via Crossref/Google Scholar/Semantic Scholar — real citations to the DOI, independent of any journal metric.
- Eventual journal IF, once published — applies only after the manuscript is accepted by a peer-reviewed title, and belongs to that journal, not to the preprint record.
Answer-First Q&A
Does bioRxiv count as published?
No. Posting on bioRxiv is not formal publication; it is a preliminary, non-peer-reviewed manuscript. Most journals do not treat a preprint as prior publication, so authors can still submit the same work to a peer-reviewed journal afterwards without disqualification.
Is bioRxiv a credible source?
bioRxiv preprints undergo screening for plagiarism, scope, and safety risks, but not scientific peer review, so credibility must be assessed manuscript-by-manuscript rather than assumed from the platform. Readers should treat findings as provisional until formal peer review or replication confirms them.
Is it okay to cite bioRxiv preprints?
Yes. bioRxiv preprints receive a DOI and are part of the citable scientific record, indexed by Crossref, Google Scholar, and Europe PMC. NIH explicitly encourages citing preprints as interim research products in grant applications.
Is bioRxiv considered a journal?
No. bioRxiv is a preprint repository operated by the non-profit openRxiv, distinct from a journal because it lacks an editorial acceptance decision, a fixed issue/volume structure, and formal peer review — the three conditions JCR and Scimago require for metric eligibility.
Implications for Research Administrators
For institutional research offices, funders, and evaluators, the practical takeaway is definitional discipline: preprint usage and altmetrics belong in a different evidence category from journal-level citation metrics, and conflating them in tenure, grant, or REF-adjacent narrative CVs misrepresents what each number measures. A downloads count on bioRxiv answers “how much attention has this manuscript attracted,” not “how citable is this journal” — the two questions require different data sources and different caveats when reported to a research-administration committee.
As preprint servers proliferate across disciplines, the underlying eligibility logic will not change: JCR and Scimago metrics remain reserved for peer-reviewed, editorially governed serial publications. What is likely to evolve is the sophistication of preprint-specific metrics — the Web of Science Preprint Citation Index and NISO’s altmetrics recommended practices are both signs that the field is building dedicated infrastructure rather than forcing preprints into journal-shaped metrics they were never built to receive.