The analytical model of Snyder and Kennedy <1983> for the whitecap coverage W and that of Srokosz <1985> for the probability of wave breaking B are developed into practically applicable forms by closely combining theoretical analysis and data fitting. The database consists of two parts: the data collected from published literature and those recently measured in the Bohai Bay. A time-averaging technique is used to estimate the fourth spectral moment of the mean Joint North Sea Wave Project spectrum. The resulting expressions are simple, in which W and B depend only on the nondimensional fetch for a fetch-limited sea. ¿ 2000 American Geophysical Union