Privation (imperfection) means the error-containing part of the structural and functional organization of an organismic system. Privation is used to measure the irreversibility of aging processes. Knowing the age rate beta it is possible to estimate the privation. Using the hypothesis that the biodynamical efficiency may not be greater than the inverse age rate beta, a dimensionless number is constructed, which is given by the product of age rate beta and the theoretical lifespan T.