The quantitative relationship between the stirrups in the plastic hinge region and the seismic performance objectives of columns, which means that the quantity of stirrups could be calculated by the ductility index, is an important issue of detail design in the current ductile seismic framework. Various calculation formulas of stirrups have been proposed by different scholars, however, most of them couldn’t satisfy the designed stirrups corresponding to arbitrary ductility coefficient. The applicability and accuracy of some existing quantifiable formulas need to be improved. The main influence factors on the ductility of solid and hollow piers are analyzed based on the analysis results from the 21 piers of research group, 135 piers of PEER, and 18 pseudo-static tests. The simplified calculation formula of confinement stirrups is regressed based on a large number of test results for columns with different sections, in which the axial compression ratio, shear span ratio, longitudinal reinforcement, concrete strength, transverse rebar ratio, and displacement ductility coefficient are chosen as the design parameters. The research results show that the proposed formula is much more suitable than those existing models to estimate the amount of confinement stirrups for various columns.