What Is h-index? A Simple Explanation (With Examples)
h-index shows up on Google Scholar profiles, CVs, and grant applications constantly, but a surprising number of researchers who cite their own h-index couldn't explain exactly how it's calculated. Here's the plain version, with a worked example.
The Simple Definition
A Worked Example
Suppose an author has published 6 papers, cited (in descending order): 25, 14, 9, 7, 3, 1 times.
| Paper Rank | Citations | Rank ≤ Citations? |
|---|---|---|
| 1 | 25 | Yes |
| 2 | 14 | Yes |
| 3 | 9 | Yes |
| 4 | 7 | Yes |
| 5 | 3 | No — 5th paper needs 5+ citations, only has 3 |
| 6 | 1 | No |
The h-index here is 4 — four papers have at least 4 citations each (25, 14, 9, 7 all qualify), and the 5th paper falls short of needing 5 citations. Adding more low-cited papers wouldn't raise it; only papers that themselves clear the next threshold would.
Why Your h-index Differs by Platform
Google Scholar, Scopus, and Web of Science each maintain separate citation databases, counting citations from different sets of indexed sources. Google Scholar generally counts a broader range of citing material, so an author's Google Scholar h-index is often higher than their Scopus h-index — neither is "wrong," they're measuring against different citation universes.
What h-index Doesn't Tell You
- Career stage bias — a brilliant early-career researcher with 2 years of publishing simply hasn't had time to accumulate a high h-index yet, regardless of paper quality
- Doesn't reward outliers — one paper cited 500 times contributes the same to h-index as one cited 20 times, once both clear the threshold
- Field-dependent norms — citation practices vary hugely by discipline, so h-index isn't comparable across fields
- Co-authorship counts fully — being one of ten co-authors on a highly-cited paper counts the same toward your h-index as being sole author
h-index vs. Impact Factor: Different Things Entirely
These get confused constantly. h-index measures an individual author across their whole publication history. Impact Factor measures a journal, typically as an average citation rate per article over a recent window. Publishing in a high-Impact-Factor journal doesn't automatically raise your personal h-index — that still depends on your own paper actually getting cited.
How to Actually Grow Your h-index
- Publish consistently over time rather than in occasional bursts — h-index rewards a sustained body of work
- Make your papers genuinely discoverable: open access, clear titles, specific keywords, and a complete Google Scholar profile
- Give it time — h-index is a lagging indicator; a paper published this year won't meaningfully move your h-index for a year or more
- Publish in venues that are actually indexed and discoverable, since an uncited, undiscoverable paper contributes nothing regardless of quality