Magnetic properties of vacuum-evaporated thin Permalloy films for memory applications are affected greatly by the thickness of the film as well as by the composition and various evaporation parameters. X-ray emission spectroscopy is generally used for thickness measurements and composition studies. In this paper, the thicknesses of nickel-iron films (81 to 82% nickel and 400- to 3560-Å thickness range) are compared by a stylus method (Talysurf), a high resolution multiple beam interferometer (Tolansky-type), and x-ray fluorescence analysis with calibrated standards. Data are presented showing that the x-ray method is the most reproducible and allows rapid calibration and computation by computers.