Scopus. Requires access through University Libraries database.
Google Scholar. Freely available
Metrics Toolkit. Helps you Navigate the Research Metrics Landscape. It is a web resource for researchers and evaluators by providing guidance for demonstrating and evaluating research impact. It includes a section on the h-Index
Publish or Perish. A software program that retrieves and analyzes academic citations, pulled from a variety of sources. It's calculations available include the h-index and the g-index.
The h-Index is a primary author level metric designed to measure research quality over time, and accounts for both the scholarly productivity and the research impact of the author. The h-Index is calculated as follows - H stands for the number of articles that have each been cited H number of times. So, an h-Index of 30 means that the author has published 30 articles that have each been cited 30+ times.
Image courtesy of Oregon State Libraries under CC-BY-SA 4.0 license
Note: An individual's h-index will vary based on the dataset. Your h-index in Scopus will most likely be different than your h-index in Web of Science because they are different datasets - the same can be said for citation counts in both databases as well.
Note: You can also create a citation report by selecting the View citation report button, which allows you to set alerts for new citations of your work, as well as export the detailed citation report (including your H-Index).