An influence of the neutrino (antineutrino) mass on the characteristics of nuclei and neutron β-deca y is demonstr ated. It has been shown that meas uring relative character istics allows one to get rid of the unknown nuclear structure, which makes it possible to determine the magnitude of the neutrino (antineutrino) mass in the β-decay processes with greater accuracy. An analysis was carried out based on general theoretical formulas for differential probabilities of the β-decays of the free neutron and tritium nucleus. As a result, it was possible to obtain simple formulas from which a theoretical estimation for the neutrino (antineutrino) rest mass can be obtained. © Published under licence by IOP Publishing Ltd.