PURPOSE: To evaluate whether preoperative magnetic resonance imaging (MRI) measurements of multiple tendon autograft sources could be used to improve estimates of intraoperative hamstring tendon autograft (HTA) diameter. METHODS: Patients who underwent anterior cruciate ligament reconstruction with HTA at our institution were identified through electronic health records. Preoperative MRI tendon measurements of the patellar tendon (PT) length, PT width, PT thickness, quadriceps tendon thickness, semitendinosus tendon (ST) cross-sectional area (CSA), and gracilis tendon (GT) CSA were conducted by 2 independent evaluators using digital imaging measurement tools. RESULTS: A total of 53 patients met the inclusion criteria, with a mean HTA diameter of 7.98 ± 0.7 mm. Height greater than 1.63 m, weight greater than 63.4 kg, PT length greater than 4.2 cm, PT thickness greater than 0.33 cm, ST CSA greater than 10.8 mm2, and GT CSA greater than 6.3 mm2 were associated with an HTA of 8 mm or greater (P < .005). Female sex was associated with an HTA of less than 8 mm (P < .05). PT length, PT thickness, and GT CSA were the strongest predictors of an HTA of 8 mm or greater and were combined into an additive logistic regression model: Score = -23.24 + (1.68 × PT length) + (20.104 × PT thickness) + (1.48 × GT CSA). If the score was greater than 0.237, the HTA graft diameter was predicted to be 8 mm or greater with 83% specificity, 91% sensitivity, and 87% accuracy. CONCLUSIONS: By combining PT length and PT thickness measurements with GT CSA measurements in a logit function model, we were able to show improved overall specificity, sensitivity, and accuracy of estimated HTA diameters in our data set when compared with assessments of anthropometric, ST CSA, GT CSA, or combined ST-GT CSA measurements in isolation. CLINICAL RELEVANCE: Preoperative MRI measurements may be used to screen whether a patient is likely to have an 8-mm graft in the setting of anterior cruciate ligament reconstruction with HTA and thus may help guide graft choice.