A Microsoft¿ Visual Basic (6.0) program, called WinAmphcal, has been developed to calculate structural formulae of both wet-chemical and microprobe-derived amphibole analyses. On the basis of the standard International Mineralogical Association (IMA-04) classification procedure, WinAmphcal classifies amphibole analyses into five groups and then determines a specific amphibole name with prefixes and modifiers. This software is developed to predict cation site allocations at the different structural positions as well as to estimate stoichiometric Fe3+ and H2O contents from microprobe analyses. If Fe2O3 content is unknown, the program calculates ferric iron content on the basis of the minimum Fe3+ (15eNK) and maximum (13eCNK) criteria considering the site assignments and stoichiometric constraints. Other user-defined calculation and normalization factors can also be carried out by current software for the process of amphibole chemical analyses. Using the charge-balance method, WinAmphcal permits the user to determine the Mn2+ and Mn3+ states from Mn3+-rich microprobe-derived sodic amphiboles. WinAmphcal stores all the calculated results in an Excel file. Hence output of the program can also be displayed and processed by any other software for general data manipulation and graphing purposes.