An automatic calculation method for thickness calculation of a deposition layer in a Fin-type field-effect transistor (FinFET) is disclosed through mapping edge lines onto an Excel spreadsheet. The similar method is also applied to the thickness calculation of superlattice or multiple quantum well for a light emitting diode (LED). The edge lines are obtained and transformed from an electronic image taken by Transmission Electron Microscopy (TEM), Focus Ion Beam (FIB), Atomic Force Microscopy (AFM), or X-Ray Diffraction (XRD) of the device.