Based on a self-consistent mean-field model, a folding form of cluster potentials has been suggested, leading to the simple parameter-free quantum tunneling calculations of various cluster decays in atomic nuclei. The mean-field-type potential provides a ground for the descriptions of both shell structure and cluster property in nuclei. The α-particle, heavier-cluster and diproton decays of even–even nuclei above magic numbers have been investigated, showing a good agreement with experimental data. The parameter-free calculation is particularly useful for the predictions of the decay properties of exotic nuclei where experimental data are scarce and self-consistent shell models have worked well.