In this paper I estimate the mass of the electrino (new lepton) through two formulas. The first formula we shall explore is the lepto-baryonic formula for the fine-structure constant which I published in a previous paper entitled: Exponential Formula for the Fine Structure Constant. Unlike the formula presented there, this paper introduces an exact formula which is given as a function of the masses of the two lightest charged leptons: the electron and the electrino; and the lightest baryons: the neutron and the proton. The second formula we shall explore is the “alpha-23” formula for the mass of the electron. Both formulas suggest the existence of a new super-light lepton which I have called: electrino. I predicted the existence of this particle in a previous paper entitled: Is the Electron Unstable?. This investigation suggests that the mass of the electrino, if this elusive particle exists, must have a value between me /529.3 and me /517.8 approximately.