In the initial steps of grass-root projects, heat exchangers cost estimation for proper decision making regarding network optimization design through pinch technology is very important. It is necessary to forecast the cost of a heat exchanger through cost estimation equations. In this article, the cost estimation equations of heat exchanger and the heat exchangers network for shell and tube heat exchangers and plate and frame heat exchangers are obtained. These equations are the function of heat transfer area by available prices in Iran. The proposed relations for Shell and tube heat exchangers are in the maximum operating pressure region of shell and tube side between 1.2–41 bars and made of two types of material: carbon steel and stainless steel 316. Furthermore, plate and frame heat exchangers relations in two regions of the inlet cold flow lower than 30 cubic meters and between 30 to 50 cubic meters are obtained. These plate and frame heat exchangers are made of stainless steel 316. Moreover, here the error of the proposed equations is studied.