Estimating source lines of code from object code: Windows and Embedded Control Systems L. Hatton Much defect data is expressed in terms of defect density (defects per 1000 lines of code) however in many proprietary systems such as Windows and also in embedded control systems, only the number of bytes of object code is normally known making it difficult to compare such systems in terms of standard measures like asymptotic defect density. This paper describes simple methods of calculating equivalent lines of code to allow such comparisons to be made and quotes estimated lines of code for various versions of Windows. The calibrations have been done for C which still dominates operating system and embedded control systems implementations. defects, object code, lines of code, estimation, Windows hatton2005a.pdf