These freely available calculators can help you compute index and factors used to judge the scholarly influence of journals and researchers. The numbers computed here are akin to the proprietary “impact factors.” By computing numerous indexes and factors you can also get a better idea at the true impact a work has.
Differences in impact factor across fields and over time by: Benjamin M. Althouse, Jevin D. West, Carl T. Bergstrom, Theodore Bergstrom Journal of the American Society for Information Science and Technology, Vol. 60, No. 1. (2009), pp. 27-34.
Why the impact factor of journals should not be used for evaluating research? by Per O Seglen, professor
Institute for Studies in Research and Higher Education (NIFU) Hegdehaugsveien 31 N-0352 Oslo Norway