Objective: This study aimed to evaluate the accuracy of standardized preoperative radiographic templating in predicting femoral and tibial component sizes across four different total knee arthroplasty (TKA) systems in patients undergoing primary TKA for osteoarthritis. Methods: This retrospective, single-center observational study included 160 knees from 141 patients (mean age of 67.3 - 7.9 years) who underwent primary TKA for osteoarthritis between March 2011 and March 2020. Of the 141 patients, 122 underwent unilateral and 19 underwent bilateral TKA. Four different TKA systems were evaluated, with 40 knees assigned to each implant group. Standardized weight-bearing anteroposterior and lateral knee radiographs were used to measure femoral and tibial dimensions using a picture archiving and communication system (PACS). The primary outcome was the agreement between radiographically predicted and intraoperatively implanted femoral and tibial component sizes. Agreement was assessed using weighted Cohen’s kappa (κ), and interobserver reliability was evaluated using the intraclass correlation coefficient (ICC). Results: For femoral components, the exact size was predicted in 76.9% of knees, and 96.8% of predictions were within - 1 implant size. For tibial components, the exact size was predicted in 64.4% of knees, and 92.5% were within - 1 implant size. Agreement between predicted and implanted sizes was substantial for femoral components (κ = 0.70, 95% CI, 0.62–0.78) and moderate for tibial components (κ = 0.54, 95% CI, 0.45–0.63). Size discrepancies differed significantly among the four implant systems for both tibial (P = 0.001) and femoral components (P = 0.010). Overall, 94.4% (302/320) of all component size predictions were within - 1 implant size. Conclusion: Standardized preoperative radiographic templating reliably predicted component size across four different TKA systems, with greater accuracy for femoral than for tibial components. When standardized radiographic acquisition, calibration, and measurement protocols are applied, conventional two-dimensional templating can provide clinically acceptable component-size predictions across different implant designs. These findings support its clinical utility as an accessible and cost-effective method for preoperative planning in primary TKA. Cite this article as: Bolat İ, Tekin M, İbrahimov J, Bozkurt O. Accuracy of standardized preoperative radiographic templating in predicting implant size: a comparative analysis of four widely used total knee arthroplasty systems. Acta Orthop Traumatol Turc., 2026; 60(5), 0811, doi: 10.5152/j.aott.2026.25811.