<p>The Hirsch index (H-index) has been used to assess journals, institutions, and organisations in both research and practice. The H-index is strongly affected by the scale of the evaluated objects, which has caused concern regarding the reliability of the results. The empirical results indicate that the size of journals has a significant effect on the H-index, which increases with journal size. This study first performed an experiment using the difference-in-differences method to verify the effect of journal size on the H-index. A new index called the equal quantity H-index (EQH) is then proposed, which uses the bootstrap method to construct a random sample of journal papers, eliminating the impact of size on the journal H-index. By comparing and analysing the evaluation results of the EQH of 59 journals in the field of information management with other indices (H-index, 2-year journal impact factor, relative H-index,<i> hq</i>₂-index, FMS journal rating results and ABS journal rating results), the robustness of EQH is verified. From a theoretical perspective, the new index, EQH, will contribute to the practice of journal evaluation and promote the development of science and technology evaluation, which is based on bibliometrics.</p>