A simple and accurate model to describe the wide band absorption coefficient cumulative distribution function is developed. The model, based on exact limiting formulations of the cumulative distribution function, explicitly expresses the absorption coefficient in terms of the cumulative distribution function, simplifying the solution of the radiative transfer equation. Parameters for the 1.38, 1.87, 2.7 and 6.3 mu m bands of water vapor are developed for a wide range of pressures and temperatures from 300 to 2900 K. The parameters for the rotational band of water vapor include temperatures from 300 to 1900 K. The results obtained with this simplified model are in good agreement with existing narrow band and line-by-line results. The simplified cumulative distribution function model provides a wide band absorption Consistent with alternate methods.