It is evident that traditional positioning systems are inadequate for positioning in closed areas today. This study investigates an ultra wide band based indoor positioning system, and its hardware designs, implementation and tests. In order to calculate the estimation of distance on the hardware, time of arrival measurement (TOA) method was used. The distance data of anchor hardwares were transmitted to the server via Wi-Fi and the position of the target was estimated by calculating it using trilateration method on the server. As a result of the tests applied on the designed hardware, a positioning system with minimum 1.55 cm and maximum 8.4 cm accuracy was realized.