Check 1 — Which metric is actually named
A real claim names a real system: the Journal Impact Factor from Clarivate, CiteScore from Scopus, or SJR from SCImago. Anything else is not a quartile system at all.
A well-documented ecosystem of invented metrics exists specifically to look like these — names in circulation include Universal Impact Factor, Global Impact Factor, Citefactor, SJIF, Cosmos Impact Factor and Index Copernicus Value, catalogued on the Misleading Metrics list maintained after Jeffrey Beall’s original work. Some go as far as impersonating established providers. "Impact Factor" is a Clarivate trademark; a journal advertising an "impact factor" from anyone else is telling you something.
Check 2 — Does the claim name a category
A quartile only exists relative to a subject category. "Q1" with no category attached is unfalsifiable, and it is the single most common tell.
Note that the reverse is not automatically dishonest. Because most journals sit in several categories and SCImago publishes a "best quartile" column, a legitimate journal may advertise a Q1 it holds in only one of its categories. That is real, but it may not be real *in your field* — which is the question you actually care about.
"Q1" with no subject category and no year attached is not a claim you can check — and that is usually the point.
Check 3 — Verify at source
Look the journal up yourself: the Master Journal List for Web of Science indexing, the Scopus source list or scopus.com/sources for Scopus, and SCImago for the SJR quartile per category. If the journal is not in the index, the quartile cannot exist, and the conversation is over.
Treat the journal’s own website as an assertion, never as evidence. Screenshots of metrics, badges and logos are trivially fabricated.
Check 4 — Look at the metric provider itself
Warning signs on the provider: an opaque site with no methodology, scores that rise every year for every journal, Google Scholar used as the citation base, and brand-new journals already displaying a quartile before they could possibly have accumulated the citations to earn one.
On the journal side, the familiar signals still apply — unsolicited invitations, guaranteed acceptance, publication in days, and fees that only become clear after acceptance.
Why this matters more than it used to
A paper published in a journal that turns out to be unindexed cannot simply be moved. It counts as published, so submitting it elsewhere would be duplicate publication, and few such publishers will retract cleanly on request. The check has to happen before submission.
It is also worth knowing that even legitimate journals lose their metrics. Clarivate suppressed 20 journals from the 2025 Journal Citation Reports for abnormal citation behaviour, and journals removed from the Core Collection lose their impact factor entirely — recent examples include Chemosphere, Science of the Total Environment and Cureus. A quartile you verified two years ago may no longer exist.