<!doctype html public «-//w3c//dtd html 4.0 transitional//en»> http-equiv=content-type> Fatigue strength of metallic components is treated as a mathematical function with the variables of probability, loading, and loading duration. In this way, one can determine both technical fatigue strength for 1 PPM and asymptotic fatigue strength with the probability of zero. A single function serves to predict outcomes for one-stage, multiple-stage, and random loading.