What is a good h-index?
There is no "good" value that holds across fields. The only sourced benchmarks are the ones Hirsch himself suggested in 2005, and they refer to physicists: about 12 for tenure at a major research university and about 18 for full professor. Outside physics, and twenty years on, treat them as a starting point only.
Detail
Hirsch's values (2005, physics)
| Situation | h-index |
|---|---|
| Advancement to tenure (associate professor) | about 12 |
| Full professor | about 18 |
| Fellow of the American Physical Society | 15–20 |
| Member of the National Academy of Sciences | 45 or higher |
The h-index grows with time
Hirsch also proposed the parameter m: the h-index divided by the number of years of scientific activity. An m close to 1 — for example h = 20 after 20 years — characterises a successful scientist. He described an h of 40 after 20 years as outstanding and an h of 60 after 20 years as truly unique. The practical rule follows: never compare the h-index of people at very different career stages.
Why there is no universal number
Citation practices vary widely between fields. The value also depends on the database it is calculated in and on the researcher's scientific age. Comparisons only make sense within one field, at a similar career length and in the same database.
What to do in practice
If a hiring call or a committee requires a minimum h-index, ask which database it is measured in and as of what date. Always state the source next to the number.