Sizes of nuclear rings against the dimensionless parameter ﹩{ \mathcal B }\propto \mathrm{CMC}/({A}_{2}^{0.3}{{\rm{\Omega }}}_{b}^{0.2})﹩ defined in Equation (12). The symbol sizes correspond to the simulation time. The dashed line draws ﹩{R}_{\mathrm{ring}}/(1\,\mathrm{kpc})=5{{ \mathcal B }}^{2}﹩, which fits the numerical results reasonably well, except for model C10 with the oval.