During the diagnosis and treatment of prostate cancer, prostate-specific antigen (PSA) levels fluctuate correspondingly following various interventions, and such fluctuations objectively and dynamically reflect the inherent characteristics and progression of the disease. Therefore, PSA-doubling time (PSA-DT), the most commonly used PSA kinetic indices, is widely adopted for risk and prognostic assessment in individual patients. PSA kinetic indices are characteristic quantities that describe the rate of PSA changes (elevation or decline). To facilitate clinical application, multiple calculation formulas of PSA-DT with different simplification levels are available, and different formulas produce disparate results. Clinicians should select suitable formulas according to specific clinical scenarios to promote the clinical guiding value of these indices.