Various measures and methods have been developed to measure the sizes of different software entities produced throughout the software life cycle. Understanding the nature of the relationship between the sizes of these products has become significant due to various reasons. One major reason is the ability to predict the size of the later phase products by using the sizes of early life cycle products. For example, we need to predict the Source Lines of Code (SLOC) from Function Points (FP) since SLOC is being used as the main input for most of the estimation models when this measure is not available yet. SLOC/FP ratios have been used by the industry for such purposes even though the assumed linear relationship has not been validated yet. Similarly, FP has recently started to be used to predict the Bytes of code for estimating the amount of spare memory needed in systems. In this paper, we aim to investigate further the nature of the relationship between the software functional size and the code size by conducting a series of empirical studies.