Advanced metering infrastructure (AMI) was a architecture with real-time two-way communications that used digital technology to monitor and manage the delivery of electricity from generation sources to meet the varying electricity demands of end users. The goal of an AMI was to provide utility companies with real-time data about power consumption and allow customers to make informed choices about energy usage based on the price at the time of use. Since the rollout of AMI was a heavy investment, a cost benefit analysis and an impact assessment should be carried out. This paper attempted to quantify the energy saving and reduction in carbon emission benefits inherent in the AMI potential. The quantitative estimation of potential saving in electricity consumption and associated reduction in carbon emission presented were based on a survey of published results, actual field measurements of local demographics in urban and rural environmental conditions, fuel mix, and possible incentive pricing based on time of use. A mathematical model was formulated to apply sensitivity analysis against the coverage of AMI in different demographics, and respective penetrations of AMI. A case study illustrated the real world application of the energy saving estimation model to Hong Kong environment. For more than 70% population participated in AMI, the emission reduction target of 19%~33% planned by Hong Kong Government could be achieved. The methodology presented in this paper could serve as a reference model in implementing AMI in other cities.