Analysis of LEACH protocol(s) using formal verification WSN nodes operate in an unattended environment and thus have irreplaceable batteries. Thus an important concern is the network lifetime; we need to utilize their energy for a longer time otherwise nodes run out of power. For this purpose various protocols have been established and the subject of our matter is the LEACH protocol. The LEACH protocol is self-organizing and is characterized as an adaptive clustering protocol which uses randomly distributes energy load among nodes. By using cluster heads and data aggregation excessive energy consumption is avoided. In this paper we analyzed LEACH and its extensions like LEACH-C and LEACH-F using Formal modeling techniques. Formal modeling is often used by researchers these days to verify a variety of routing protocols. By using formal verification one can precisely confirm the authenticity of results and worst case scenarios, a solution not possible using computer simulations and hardware implementation. In this paper, we have applied formal verification to compare how efficient LEACH is as compared to its extensions in various WSN topologies. The paper is not about design improvement of LEACH but to formally verify its correctness, efficiency and performance as already stated. This work is novel as LEACH and its extensions according to our knowledge have not been analyzed using formal verification techniques.