Switched Capacitor Converters (SCC) losses are analyzed and the rules for the selection of SCC parameters (such as switch resistances, capacitors values and switching frequency) to meet specific efficiency requirements, are developed. This is done by first applying an advanced methodology for calculating the equivalent resistance (Re) of the SCC in general. The impact of each of the parameters on the equivalent resistance is then analyzed and the results are used to develop design rules to meet efficiency targets as defined. The paper clarifies an apparent paradox related to the role of switch resistances in SCC which seem not to affect the efficiency considering the fact that the efficiency is determined by the SCC voltage transfer ratio. The results of this study could help designers of SCC to select optimal values of the SCC parameters that will meet specifications. The analysis developed in this study can also assist users of SCC to better understand the characteristics and limitations of commercially available SCC.