BACKGROUND Various sizes of implants need to be available during surgery. The purpose of this paper is to compare body height and shoe size with implant sizes in patients who underwent total knee replacement surgery to see which biomarker is a better predictor for preoperative planning to determine implant size. METHODS A total of 100 knees, belonging to 50 females and 50 males, were observed. Participants' body height and shoe size were collected and correlated to implant sizes of a current, frequently used, standard total knee replacement (TKR) implant. The femoral anteroposterior and mediolateral width and the tibial anteroposterior and mediolateral width were correlated with height and shoe size. RESULTS The correlation between shoe size and the four knee implant dimensions, femoral AP, ML, and tibial AP and ML were higher than the correlations between height and the same four dimensions. CONCLUSIONS The results indicated that shoe size is a better predictor of component dimensions than is body height.Level of evidence: III.