Approximate calculations of the bounded jet have been carried out by adding an assumption for the diffusion width of the bounded jet to the velocity distribution on the center-plane of the bounded jet which was already proposed by the authors. In order to determine the parameter contained in the assumed velocity distribution function and to compare the results of calculation with those of experiments, the experiments have been done, as an example, using a nozzle having an aspect ratio of 1. As a result, the approximate calculations of the velocity distributions on the center-plane, the diffusion width and the isotach patterns of the bounded jet agree well with the experimental results regardless of the initial turbulence intensity and the downstream location.