Increasing demand for the mobile, low energy systems has laid emphasis on the development of low power processors. Low power design has to be incorporated into fundamental computation units, such as multipliers. The optimization of the energy-delay product in such low power multipliers will enable energy efficient computation. This study proposes a power estimation tool to analyze different array multiplier architectures, which are most commonly used in such applications. Gate level library design parameters are utilized to derive energy-delay performance for any given set of input vector patterns, and multiplier size. Vector and size dependent factors are therefore clearly identified. Examples are provided from carry save array multiplier (CSAM) and ripple carry array multiplier (RCAM) to demonstrate the capabilities for the tool.