NSOL A numerical calculation program of molecular surface area, volume, and solvation energy. In computer simulation of proteins and nucleic acids, such as MD and/or MC, conformational energy + solvation energy calculation is needed. However, solvation energy calculation (implicit water, PB, RISM, etc.) is very time consuming. Therefore it can be applied to small system, or it can be included as implicit solvation effects, such as continuum model using distance dependent dielectric constant. While, there exist two methods that calculate solvation energy using solvent accessible surface area; ASP (atomic solvation parameters) model and GB/SA. In these methods, as solvent accessible surface area calculate fast, solvation energy could be calculate fast. So I decided to develop fast algorithm for molecular surface area calculation. NSOL is a fast solvation energy calculation program using fast molecular surface area calculation algorithm.