In this paper, an easy-to-program mathematical expression to compute the Envelope Correlation Coefficient (ECC) between two antennas by using their radiated electric fields at the far-field region is derived. The main advantage of the resulting algorithm is its higher speed to obtain results compared to those used in commercial software. This novel approach presents a discrete equation that can be employed after obtaining the electric field in spherical coordinates by computer simulations. Thus, another alternative arises to report this metric for low or high radiation efficiency antennas, instead of the less accurate S-parameter-based equation, which does not ensure high accuracy when low radiation efficiency antennas are under study. A comparison between the presented algorithm and the results given by commercial software is shown and discussed, in which is clearly observed that the results are greatly convergent, but with the advantage of achieving a lesser time computing period by the proposed method.