Location fingerprinting utilizes periodic beacons transmitted by Wireless Local Area Network (WLAN) Access Points (APs) to provide localization in indoor environments. Currently no method is able to quantify the effectiveness of localization information provided by individual APs. Such a metric would enable the optimal placement of new APs as well as eliminating redundant APs so as to reduce the resources consumed by indoor localization software in client devices. This paper proposes LocationInfo, a metric that utilizes walk test data for quantifying the localization efficacy of APs. The performance of LocationInfo is evaluated using two experimental settings. First, it is used for identifying the optimal location for new APs. Second, it is used for filtering out excess APs in a crowded WLAN environment. In both experiments, LocationInfo outperforms existing metrics.