Many aspects determine the quality of scientific journals. The impact factor is one of these quantitative parameters. However, the impact factor has a strong dependence on the journal discipline. This dependence forbids a direct comparison between different journals without introducing external considerations. In this paper, a renormalized impact factor, F_r, inspired in the definition of dimensionless physical parameters, is proposed. F_r allows a direct comparison among journals classified into different categories and, furthermore, the time evolution analysis of the journal's role in its field.