Size is one of the important attributes of a software product. Lines of Code (SLOC or LOC) is one of the most widely used sizing metrics in industry. The amount of effort needed to maintain a software system is related to the technical quality of the source code of that system. Estimation of effort is complicated and challenging task in software industry. Project size is a measure of problem complexity in terms of effort and time required to develop the products. This paper mainly focuses on Impact of LOC on complexity. SLOC is typically used to predict the amount of effort that will be required to develop a program, as well as to estimate programming productivity or complexity once the software is produced.