Generalizing the Drude conductivity and using experimental data for the complex refractive index or for the complex dielectric function an expression is derived for the determination of the frequency-dependent electron mass, defined as the optical mass. Values for the optical mass are calculated for 27 metals, including in a few both the solid phase and the liquid phase. Additionally, a new formula for the estimation of the polarizability of metals is given and evaluated for 15 metals. Good agreement between existing published literature values and our calculation is found for the optical mass in the zero-frequency limit as well as for the polarizability.