In electrical industry, deregulation intended at creating economical markets to do business with electricity. Many utilities provide transaction services for wholesale customers, they must know about the post information on ATC of their transmission networks. Such information will help power marketers, sellers and buyers in reserving transmission services. ATC must be rapidly updated for new capacity reservations. Various mathematical models have been developed by the researchers to determine the ATC. ATC is an impending question in the conceptualization of deregulation in addition to congestion management and pricing. This research work follows a line of investigation of calculating ATC using AC- power transfer distribution factors (AC-PTDF) and its enhancement using flexible AC transmission system (FACTS) devices like static compensator (STATCOM) and unified power flow controller (UPFC). This solution eliminates extravagance in erecting new transmission system. FACTs devices whose settings are optimized using cuckoo search algorithm (CSA) are placed by accounting sensitivity of lines to provide reactive power that recuperates the ATC of the desired line. Undoubtedly, it is very important and imperative to carry out studies on exploitation of FACTS technology to enhance the ATC. The Bilateral and multi-lateral transactions are randomly chosen and tested in IEEE 30 and sample 6 bus system.