g-Index (Egghe)
Also known as: Egghe g-index, Egghe index, g index
The g-index, introduced by Leo Egghe in 2006, is an author-level bibliometric indicator designed to repair a structural weakness of Hirsch's h-index: its insensitivity to the size of the most-cited papers. Where the h-index caps the credit any single paper can earn at h, the g-index lets exceptionally cited articles raise an author's score. It is defined as the largest number g such that the g most-cited papers together accumulate at least g-squared citations. Because it rests on cumulative rather than per-paper citation counts, the g-index always equals or exceeds the h-index and rewards researchers whose impact is concentrated in a few landmark works as well as those with broad, steady output.
Key highlights
- Gives extra credit to highly cited papers, correcting the h-index's insensitivity to the magnitude of citations above the h-core.
- Always at least as large as the h-index, and the gap between them summarizes how concentrated an author's impact is.
- Single, intuitive number computed from the same ranked citation list as the h-index, so it is cheap to add to any evaluation.
- Better discriminates among authors who share the same h-index but differ greatly in the citation counts of their top papers.
Intuition
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How it works
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When to use it
Use the g-index when you want an author-level impact measure that rewards highly cited landmark papers rather than treating all papers in the productive core as equivalent, and when comparing researchers whose citation distributions are skewed by a few standout works. It complements the h-index in evaluations of individual scientists, grant applicants, or job candidates where the h-index would understate the influence of exceptional articles. It is less appropriate for cross-field comparisons, where citation cultures differ and a field-normalized indicator is needed instead, and it inherits the h-index's dependence on a clean, correctly attributed publication set. Because g can be inflated by a single extreme paper, it should be read alongside the h-index and the underlying citation distribution rather than in isolation.
Strengths & limitations
- Gives extra credit to highly cited papers, correcting the h-index's insensitivity to the magnitude of citations above the h-core.
- Always at least as large as the h-index, and the gap between them summarizes how concentrated an author's impact is.
- Single, intuitive number computed from the same ranked citation list as the h-index, so it is cheap to add to any evaluation.
- Better discriminates among authors who share the same h-index but differ greatly in the citation counts of their top papers.
- Sensitive to a single extreme outlier paper, which can inflate g and overstate sustained impact.
- Not field-normalized, so it is unfair across disciplines with different citation densities and publication rates.
- Inherits the h-index's dependence on accurate, deduplicated author publication and citation data.
- The convention of appending fictitious zero-citation papers when total citations are large relative to paper count is unintuitive and treated inconsistently across tools.
Common pitfalls
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Applications
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Frequently asked
How exactly is the g-index defined?
Rank an author's papers in decreasing order of citations and consider the cumulative number of citations of the top g papers. The g-index is the largest g for which this cumulative total is at least g-squared. Equivalently, it is the largest g for which the top g papers have an average of at least g citations each. Because the criterion is cumulative, citations from very highly cited papers carry over and let g extend deeper into the list than the h-index would.
Why is the g-index always at least as large as the h-index?
The h-index requires that the h-th paper individually has at least h citations, while the g-index only requires that the top g papers collectively have at least g-squared citations. The cumulative condition is weaker than the per-paper one, so any value satisfying the h criterion also satisfies the g criterion. Egghe proved that g is therefore always greater than or equal to h, and the size of the gap reflects how skewed the author's citation distribution is.
When can the g-index be misleading?
Because it uses cumulative citations, the g-index can be driven up by a single extraordinarily cited paper, so it may overstate an author's sustained productivity. It is also not normalized across fields, making cross-disciplinary comparison unfair. For these reasons the g-index is best reported alongside the h-index and an inspection of the underlying citation distribution, rather than as a standalone ranking number.
Sources
- 1.Egghe, L. (2006). Theory and practise of the g-index. Scientometrics, 69(1), 131-152.
- 2.Hirsch, J. E. (2005). An index to quantify an individual's scientific research output. Proceedings of the National Academy of Sciences, 102(46), 16569-16572.
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Cite this page
ScholarGate. (2026, June 23). g-Index (Egghe). ScholarGate. https://scholargate.app/bibliometrics/g-index