Based on the Santhosh formula (Nucl Phys A 825:159, 2009), considering the blocking effect of unpaired nucleons and the orbital angular momentum taken away by the emitted α particle, we put forward an improved formula to evaluate α decay half-lives for superheavy nuclei. Using this formula, we systematically investigate the α decay half-lives of 141 nuclei ranging from Z = 96 to Z = 118 with the corresponding root-mean-square (rms) deviations being 0.319 , 0.619 and 0.388 for 41 even–even, 78 odd-A and 22 odd–odd nuclei, respectively. In addition, this improved formula is generalized to predict α decay half-lives for 100 nuclei with Z = 117, 118, 119 and 120. For comparison, the predicted results obtained by using phenomenological formulae, semi-microscopic and/or microscopic models are also present. The corresponding predictions consistently indicate that N = 184 may be the next possible neutron magic number. [ABSTRACT FROM AUTHOR]