In this paper, we consider the downlink in a K-Tier heterogeneous network in the presence of Nakagami-m fading and noise. For such a system, we derive closed-form approximations of coverage probability and average rate achievable. A piece-wise linear approximation is employed in obtaining the simplified expressions. The proposed results are verified numerically through simulations. A comparison with existing work shows that the proposed work is a good approximation. © 2018 IEEE.