To calculate the g-index, follow these steps: 1. Order a researcher's publications in descending order based on citation count. 2. Calculate the cumulative number of citations for the top n papers. 3. Identify the largest number g such that the top g papers have at least g2 citations in total. For example, if the top 3 papers have a combined total of at least 9 citations, the g-index would be 3.