Isospin dependence of the oscillator spacing

New improved expressions for the oscillator spacing [h bar][omega] are derived. These expressions have the advantage of being isospin dependent. They are obtained by employing new expressions for the mean square radius of nuclei, which fit the experimental mean square radii and the isotopic shifts of even-even nuclei much better than other frequently used relations. The trend of the variation of [h bar][omega] with the neutron excess is studied. A formula for [h bar][omega] calculated in the present approach as a function of the mass number [ital A] agrees well with [h bar][omega] coming from a completely different input, i.e., the separation energies of the last nucleon. Very accurate approximate asymptotic formulas for [h bar][omega] are also derived, which are suitable for practical use.