We propose a semi-analytical model for the quantum dots spectra that accounts for the space dependence of electron (hole) effective mass and the effective mass anisotropy of the dot material and of the surrounding matrix. This dependence and anisotropy significantly affect the position of the quantum levels. Our analysis shows that quantum dot spectra are relatively insensitive to the exact shape of the quantum dots. The model is verified by the comparison with the previously reported numerical calculations of the InAs quantum dot spectra.