Extended definition
Quartile classification (Q1/Q2/Q3/Q4) is the classification of journals into four quartiles within a subject category, based on ordering by an underlying bibliometric metric — JIF, SJR, or CiteScore. Q1 holds the top 25% of journals ranked in the category; Q2 the second quartile (25% to 50%); Q3 between 50% and 75%; Q4 the bottom 25%. The subject category is defined by the database originating the metric: Web of Science Categories for JIF, Scopus Subject Areas for SJR and CiteScore. Since categories differ between databases, the same journal can appear in different quartiles depending on the source; and within the same database, multi-area journals can have different quartiles in different categories. Quartile classification has replaced, in much of editorial practice and institutional evaluation, the use of raw numerical metrics — because it allows relative comparison within a field without the false precision of comparing absolute numbers.
When it applies
Q1-Q4 classification is the standard criterion in academic evaluation systems in many countries: European funders, institutional evaluation agencies (Italian ANVUR, Spanish ANECA), funding agencies. In some national systems, parallel local classifications operate with similar logic but distinct categories. Researchers use quartile to select target journals: Q1 for maximum visibility and prestige, Q2-Q3 as strategic alternatives with less competition. Universities use quartile in promotion and progression decisions and in institutional rankings. Professional bibliometric analyses always report quartile alongside the absolute number.
When it does not apply
It does not apply for cross-field prestige comparisons — a Q1 journal in humanities and a Q1 in biomedicine have radically different citation loads in absolute terms. It does not replace qualitative editorial analysis of the journal (scope, review time, editorial policy, audience). For new journals or small fields, quartile can oscillate dramatically year by year due to few comparison peers. It does not apply as a quality signal for individual articles — citation distribution within any Q1 is still skewed. DORA (2012) and CoARA (2022) recommend that quartile not be the sole criterion in career decisions.
Applications by field
— Institutional evaluation: most university systems today require Q1/Q2 for promotion or progression. — Funding calls: many agencies require or prioritize publications in Q1. — Submission strategy: target journal selection at planning stage; Q2-Q3 set as second option in case of Q1 rejection. — Bibliometrics: quartile is the standard axis in mapping institutional or national output.
Common pitfalls
The first pitfall is confusing quartiles across databases — Q1 SJR, Q1 JIF, and Q1 CiteScore are not equivalent; the same journal can be Q1 in one database and Q2 in another. The second is ignoring multi-area categorization: many journals are in two or three categories with different quartiles in each — using the best for self-promotion and the worst for criticism is a debatable bias. The third is treating Q1 as a certificate of individual quality; it is a journal-level statistical signal, not an article-level one. The fourth is not considering longitudinal movement: a journal that was Q1 five years ago may have dropped to Q3 — the metric refers to the publication year, not the lookup year. The fifth is privileging Q1 in all situations: in fields where Q2 is the realistic ceiling for serious publication (some humanities and small disciplines), demanding Q1 distorts what counts as legitimate output.