h-index
What is a journal's h-index?
A journal's h-index is the largest number h such that h of the journal's papers have each been cited at least h times. A journal with an h-index of 120 has published at least 120 papers that have each drawn at least 120 citations. It folds quantity and citation impact into one figure, it is cumulative over the journal's whole indexed history, and — because it rewards volume and age — it is not comparable across fields or between a young journal and an established one.
Definition
The h-index was proposed in 2005 by the physicist Jorge Hirsch as a single number summarising a researcher's output and its citation impact together: a scientist has index h if h of their papers have at least h citations each and the remaining papers have no more than h. Applied to a journal, the same rule runs over the journal's papers instead of one author's.
The construction makes it deliberately insensitive to extremes. A handful of very highly cited papers cannot lift the index on their own, and a long tail of uncited papers cannot lower it. What raises a journal's h-index is a broad body of papers that are each cited reasonably often.
Where the number on our profiles comes from
The h-index on each journal profile is the one OpenAlex publishes for the journal, computed on its open citation graph over every work OpenAlex has indexed for that journal. We load OpenAlex's value into our venue index and show it with the date the index was built; we do not recompute it. It is not Scimago's h-index, which is computed on Scopus data: the two databases index different sets of papers and citations, so the two figures can differ for the same journal, and a journal outside Scopus can still have an OpenAlex h-index.
Because it counts every paper the journal has ever had indexed, it is cumulative: in practice it rises or stays flat from one year to the next, and it only falls if papers or citations are removed from the index or the index is reprocessed.
What it rewards, and what it hides
Read the h-index with its structural biases in mind:
- Volume — a journal that publishes thousands of papers a year has far more candidates for the 'h papers cited h times' set than a journal publishing eighty. Size alone raises the ceiling.
- Age — an index that never resets favours journals that have been indexed for decades over strong journals founded recently, whatever the quality of what each publishes today.
- Field — citation habits differ by discipline, so an h-index that is exceptional in mathematics is unremarkable in molecular biology. Compare within a field only.
- It is not a rate — it says nothing about how often a typical recent paper is cited. For that, look at the two-year cites-per-paper figure or the SJR on the same profile.
Reading it beside the other metrics
Each figure on a journal profile answers a different question. The Scimago quartile gives the journal's relative position in its subject category this year; the two-year cites-per-paper rate gives how often a recent paper is cited; the SJR gives that rate weighted by the prestige of the citing journals; and the h-index gives the size of the journal's cumulative citation footprint. A high h-index with a modest quartile usually means a large, long-established journal whose recent citation rate is ordinary; a high quartile with a small h-index usually means a newer or smaller journal doing well right now.
The profiles at /journals are free to browse. To find journals that fit a specific manuscript rather than compare metrics, the Journal Finder costs 15 credits per run and ranks candidates by topic fit with these figures beside each one.