Electric-field acceleration factor β is the slope of the log (tBD) versus Eox curve, where tBD is the time to breakdown at oxide field Eox. We report that β is not a constant but proportional to Eox−2. This is the main cause of the wide divergence of β values reported in the literature. The reported oxide thickness dependence of β is believed to be a result of the higher electron trap densities in thicker oxides. Oxide lifetime extrapolation using log (tBD), or better, log (QBD) against 1/Eox plots is more accurate and has a theoretical basis. Highly accelerated oxide testing appears to be feasible especially for very thin oxides.