The half-lives for the even–even (e–e), even–odd (e–o), odd–even (o–e) and odd–odd (o–o) nuclei in the range 100 < Z < 120 have been tested within the Viola–Seaborg formula (VSF) and within the analytical formula of Royer (RF). We proposed another formula (Present Work Formula or PWF) with regard for the effect of angular momentum of the alpha decay particle and with the use of the relative neutron excess (︀(N−Z)/A)︀. Our formula includes a new set of parameters found by the least square fitting method of alpha decays of 128 nuclei. We obtained the standard deviations for each of the formulas for comparison. The results show an acceptable agreement with available data. The values of the suggested theoretical coefficient (K) for the PWF show a similar behavior of half-lives with a-decay, which can be used to predict the new superheavy nuclei.