The theoretical defect size distribution has been derived on the basis of the kinetic formation and growth parameters. Formulas are derived for the mathematical expectation and variance for the damage in a uniformly strained material. The damage nonuniformity occurring with a Poisson distribution for the defect size in the bulk can have a substantial effect on the forecast working life. Phenomenelogical results are obtained for the working life as a function of mean defect size and generation rate, together with ones for the failure probability and the deformed material volume.