Restructured power system helps to meet the active power requirements of the consumers in an effective way. In an Independent System Operator (ISO) model of restructured power system, Available Transfer Capability (ATC) is calculated so as to determine how much extra power can be injected into one site apart from base consumption. ATC computation plays a significant role during power transactions because it helps the participants to schedule their transaction more effectively and quickly. This paper mainly focuses on ATC calculation using linear sensitivity factors for normal mode and line outage mode. © 2017 The Authors. Published by Elsevier Ltd.