An expression for the magnetic moment of a massive Dirac neutrino was deduced in the context of the electroweak interactions at the one-loop level in 1977. A linear dependence on the neutrino mass was found. In addition, a magnetic moment for a massive neutrino arising from gravitational origin is predicted by the so-called Wilson-Blackett law. The latter relation may also be deduced from a gravitomagnetic interpretation of the Einstein equations. Both formulas for the magnetic moment can be combined, yielding the value of the neutrino mass.

The gravitomagnetic moment, i.e., the magnetic moment from gravitational origin, may contain different *g*-factors for the massive neutrino eigenstates *m*_{1}, *m*_{2} and *m*_{3}, respectively. Starting from the Dirac equation, a *g*-factor *g* = 2 has been deduced for a neutrino in first order, related to the derivation of the g-factor of charged leptons. When a value *g* = 2 is inserted, a value 1.530 meV results for the lightest neutrino mass *m*_{1}, the main result of this work. In addition, the remaining neutrino masses can be calculated from observed neutrino oscillations.

Our results for the neutrino masses are compatible with the three-parameter semi-empirical neutrino mass formulas obtained by Królikowski. In addition, an empirical relation between the three neutrino masses proposed by Sazdović yields neutrino masses in fair agreement with our results.

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